Even forgetting about the ridiculously wage inflation, I'm still trying to get my head around the thinking that cleaners should be paid the same as teachers. 
Why the hell would anyone want to be a teacher if you could get the same money as a cleaner? Granted there would be a few (but it would be a few) people who would still want to follow their vocation, but how long do you think that would last?
Would you really expect well qualified professionals, not just teachers, to go through the stress of the training and qualifying and the daily stresses of the job just to be paid what had become the new minimum wage. The same wage as a shelf stacker or cleaner?
You'd very quickly end up with far lower quality teachers and nurses, etc, because for every good quality candidate who would still go for the teaching/nursing job at NMW, there'd be another 10 who would just say 'sod that' and go for the cleaning job on the same pay. Hence you'd end up having to accept less well qualified and less suitable candidates into professional positions.
It really is beyond ridiculous. In one fell swoop you would have taken away any incentive for 90% of people on NMW to try to improve their lot, while simultaneously killing the economy stone dead.
I'm also baffled by those who are talking about going back to the days of slums and outside toilets etc. Why do you think things have improved so much over the years?
Yes, the welfare system has allowed those less able (or willing) to provide for themselves to have a decent basic livelihood, but where do you think the money comes from to pay for it?
It comes from the fact that country has prospered from free trade, minimal regulation, specialisation and property rights. This prosperity has allowed, through taxation, the improvement of the welfare state to where it is now. It's not a 'zero sum' economy; it doesn't rely on one person being poor to make another rich, as difficult as that is to understand for some people, so why should you take away a footballers share of the wealth he's creating? It wouldn't suddenly mean there'd be more money for someone else, it would just mean a lower tax-take for the government! 