We say that companies should pay higher wages when they are asking people to work extra hours or on zero-hours contracts.
Actually that by itself should do it. Make the minimum pay to be 2x statutory minimum on zero hour contracts as well as any overtime up to a full 37.5 hour week on part time ones. I suspect that they will not have the guts to do that though (*).
Top this up by prohibition of any contractual relationship between a company and self-employed at tax level. Only physical persons can employ a self employed which is not registered as a company or at least sole trader. You want to be "self employed" which works for Uber - fine, company house, LTD and proper accounting please. Nothing personal, just business - I am paying a 5 digit sum in taxes and NI per year and while I am happy for this to go to people who are in need, any ideas that it should pad scumbags like Uber or Delvieroo bottom lines is off the menu.
This will sort the whole Gig Economy/Sports Direct situation overnight.
(*)Time to get on "write to them" and send a Christmas card to my MP on this subject I guess