I was a member of Unison (one of the UK's biggest unions, ~2million members) for about 6 years. Since then I've been working private sector (unionless) for about 5 years. I went on strike with them over public sector pay and conditions a number of times and even helped with some organising. As such, I know just a bit about unions in the UK and can hardly be called unobjective on the issue as I have a fairly even spread of experience both inside and outside of union circles.
About 25% of the British workforce is a member of a union. Not many people today spend their whole lives only in organised workplaces. Believing you have special knowledge means, in fact, that you have very little knowledge.
And you can certainly be called subjective while you're talking about your personal experience. Indeed, Unison is probably the best example of an overly politicised union, as well as being completely public sector, so unrepresentative of a mostly private sector workforce.
It has to do with the fact that the UK has excellent employee protection laws
Compared to much of Europe, no it doesn't - and they're being thoroughly diluted.
such that unions are now entirely unnecessary for any reason other than to ensure those laws do not get weakened
That is one important purpose of unions, and the decline in membership has meant a corresponding weakening in labour laws. Unions also exist to ensure that labour laws are kept up-to-date, but this political angle that you perceive to be a major role is in fact a minor role, more relevant for associations of unions (e.g. the TUC).
The main purpose of a union is to facilitate a dialogue between the two sides of industry, primarily providing the voice of the workers. Workers present the grievances which cause higher staff turnover, lower productivity and (in the worst cases) desperate dishonesty, and management provide solutions which fit in with the organisation's constraints (profit or budgetary). In order to do this, unions keep their members informed about the law and company practices. They monitor for both statutory and non-statutory abuses. If negotiation should fail, they provide legally trained staff to represent their members.
we have strong health and safety laws, we have a very decent minimum wage, we have excellent redundancy terms and protection, we have excellent protection against unfair dismissal, we have incredibly strong equality laws, we have an effective industrial tribunal system, we're soon to have enforced pension provision, and so on.
With the exception of health & safety and the vague comment about pension provision (we've always had pension provision!), you evidently have no idea what you're talking about. You're just listing random protections you can remember vaguely that UK workers have, and adding words like "excellent", "incredibly strong" and "effective".
You also neglect to recognise that it is precisely unions which tend to provide representation. I am legally educated and have informally assisted with UT cases, FWIW. A few factoids to get you thinking:
decent minimum wage: Those on JSA for more than a year (less for youth), and with the WRA 2012 even those declared unfit for work, can be and in the former case already are required to work in regular jobs in profit-making establishments up to 30 hours per week for no pay beyond the JSA amount. The usual suspects (Tesco, Poundland) clearly let go of their regularly employed workforce to take advantage of this sidestepping of the minimum wage laws. It doesn't take a mathematician to work out what the effective rate of pay is.
redundancy terms and protection: Obviously you've never lived in mainland Europe.
unfair dismissal: Getting gradually worse - I assume you were asleep when the Unfair Dismissal and Statement of Reasons for Dismissal Order 2012 was passed.
equality laws: On the contrary, proving discrimination is extremely difficult except in the well-established area of gender discrimination (being backed up by a disproportionately huge amount of EU law). And good luck getting EHRC funding - a discrimination case will be hard to prove and may require substantial medical evidence for disability.
industrial tribunal (although it's not been called that for a long time): Actually, the system is fairly lame - most cases are settled or withdrawn before hearing, and the employee in general will fail at hearing or (more often) pre-hearing. Consider, for example, table 2.2. The Enterprise and Regulatory Reform Bill will make things more hairy for employees, and some (quite hefty - especially for discrimination, surprise surprise!) fees are being introduced in 2012. As good a summary as any.
I imagine you're just another disillusioned kid turned Tory because you felt that one particular union wasn't delivering and lucked out in the private sector. I take heart in the fact that absolute union membership in the private sector has gone up since that buffoon Cameron and his ship of fools took control.
Besides, your underlying assertion that Germany is somehow better than the US or UK is pretty much false anyway. The US outdoes Germany by most metrics, the UK outdoes it by many.
Exports per capita: Germany.
Best labour laws and most effective unions: Germany.
Sustainable public sector exists: Germany.
I'm not going to read your response because it is apparent that I'm speaking to someone who has a lot of opinion and not much knowledge. I have merely provided this post to give you a few things to think about.