Sure, let's go, I'll start:

Poverty, unemployment, lack of opportunities, industries destroyed, invisibilisation of the working class, not wanting to die out in the streets because your country has potentially no or bad social nets, destruction of said social nets forcing people to take even miserable jobs. We can go on.

Here's a hint for you, since it's your turn: the amount of people doing Uber because they love driving people around a traffic-jammed city in a 300000km piece of shit car is close to zero

How is any of that Uber’s responsibility or in their capacity to solve? Every single one of those issues is societal, which can only be solved by the people and their government.

"Lads, is it immoral to abuse the misery and despair of people to make money?"

Increasing the demand for labor increases prices for labor sellers. I do not see how it could be construed as worse than not creating that increase in demand.

If workers are choosing DoorDash, it seems like your ire should be directed at all employers other than DoorDash who are offering a worse or no deal to them.

I talk to a lot of Uber drivers who seem to enjoy driving for Uber. I can imagine times in my younger life when I'd have enjoyed it as well.