I think some artists want to appeal to the poorer people so pricing their tickets higher or letting the free market work out the price would damage their reputation. So it doesn't seem to be a real problem we need to solve. It's a problem some artists feel they have. Let them figure it out.
If I was an artist and I expected a full venue with tickets that cost 10, I'd start selling them at 1000, then at 500, 200, 100, 50, 20 and finally 10. If someone buys all of them at 1000 and only that person shows up - awesome! Maybe there will be less drug sales because 1 person bought all tickets but that 100x per ticket could be used to pay the vendors.
Because there is demand for it. A lot of people like going to live music and theatre events and scalpers make it more difficult and more expensive for them.
Why shouldn't anything be done? Because capitalism is God?