I got a Wonga loan a few years ago. I needed £80, I couldn't get the money from the bank in time and no guarantee I'd have got it at all. I didn't want to borrow from family for very particular reasons, plus would have been hard pushed to get the money in time. I needed the money very short term (could pay it back within 3 weeks.)
It worked well for me in very particular circumstances. It was well worth the £16 it cost me. If I hadn't been able to get that loan it would have cost me at least 10 times as much and probably a great deal more.
So, it's hard. You need to be utterly disciplined to borrow that way and that's unlikely to apply to most of their customers (I wouldn't have been in the position of needing the loan if our family finances had been more disciplined in the previous 6 months).
They, like the banks, will just not lend if their profit margins are not high enough, and the default rates for that sort of business are extremely high - other customers have to pay for those defaults.
I don't know how you make lending to very high risk customers more attractive without charging huge interest? Would taxpayers be willing to underwrite loans to people like me back then? I paid the loan back, but things were on a knife edge for me at that time. It wouldn't have taken much bad luck to have pushed me over.
Financial education is a MUST, but it is very, very hard to tell someone who has few nice things that you can't have that thing you really want/need from Brighthouse because it "just doesn't make financial sense dear" . If you have £5 per week you can maybe get a fridge from there. You might not have the £50 all at one go to get one from Gumtree or the British Heart Foundation shop.
My mind boggles trying to work out what's for the best. I hate the payday lenders, but I'm not sure that cheap, easily available credit is possible. And if credit is not possible for the high-risk from legitimate lenders then the crooks will provide it. People won't just stop borrowing.