Its not quite that simple.
Glass - really easy to recycle, we have even been doing this for decades in the UK. Only thing is, you have to sort it by colour first or it cannot be recycled, except as glass that is used in non-consumer areas.
Metal: easy to recycle, ferrous material is even easier as a big magnet can sort it. The rest is basically aluminium from drinks cans.
Paper: can be easy, but not if its contaminated with plastic (eg windowed envelopes) or plastic (coated to make it shiny). Even then, there's a limited recycling cycle for it, but it can still be burned in the end.
Plastic: now we get a problem. There are so many different types, (you can see them on your products by looking for the number inside the recycle triangle). Then there's problems with the colours - put black plastic in with the rest and it can only be turned into more black plastic. The prices for most plastic is so low that its often cheaper to just chuck it in the garbage.
Ultimately sorting at source is the only option to make recycling cost effective (and even then, if one neighbour decides to stuff his rubbish in the recycling bin, none of the lorry load that collected it gets used).
Round here, we do plastic in bags; metal, paper and glass in bins. I used to live in a place where you could put the latter 3 in a single bin as sorting that was relatively easy, but they didn't take plastic at all.
There are ways to encourage recycling like we used to do: community groups could collect things like paper, you'd store them until a church or scout group would turn up to collect bundles of one type of material (say, papers) where they would take them to be recycled and possibly even get paid for them as the bundles would be properly sorted and thus worth a lot more, or you could just put a penny deposit on glass or metal that could be refunded on return.
BTW, Ars had an interesting tour of a recycling centre: