It's not idealistic to think companies would suddenly pay decent wages if government intervention ceased, it's basic Austrian economics.The key here would be to look at what companies do now – how many go beyond the absolute minimum they have to? John Lewis is one, given that it's a co-op and therefore the bulk of employees share in the success of the company in real percentage terms (versus getting a 50 quid 'Christmas bonus' or whatever, when your company makes a ton of cash). But that system is very rare.
Not technically a co-operative, but close enough (don't ask me what the difference is but it's there).
All employees (Partners) share the bonus, which is the same percentage for everybody, from the lowest-paid shop assistant to the chairman (not CEO) of the company. This year's Partnership Bonus was 6%. A quick google of competitors (such as Sainsbury and M&S) suggest that their equivalent bosses get bonuses of between 100% and 700% - on top of pay rises and share options they seem to award themselves, even in the same weeks as cutting christmas bonuses to their retail assistants...
Now and again other companies have looked at the JLP to find out why partners seem more motivated than in other companies. They quickly lose interest when they realise they'd have to give away their companies in Trust to their employees to copy the same business model.