I guess you haven't been following it as closely as you think you have because Vince Cable's excuse was that Google is not doing anything illegal.
The simple fact is that the Tory party does not want to close these loopholes because many of their friends make use of them. They make some noise about it, go on Radio 4 and Newsnight and announce it in the Commons, but are careful not to really do anything.
The problem with only paying what the law requires is that these companies then arrange their corporate structure to avoid paying almost anything, against he spirit of the law. It then becomes a game of cat and mouse, except that parliament moves so slowly the mouse always finds a new hole to dive down as soon as there is talk of closing the old one off. You can't easily legislate to make them pay more tax, although it looks like the EU might have found a way to do it if every country acts simultaneously.
Maybe the last line of any tax law should be "no funny games".
Oh, and don't forget Google did actually lie. They said there were no sales done in the UK, yet most of their staff list sales as part of their duties on their CVs and in their job titles.