I myself tried many apps to earn money but there was no a single app which could give me good amount of money. Some apps do give points which can be converted into money but those earned so less and you have to do a lot of work.
We quite have the same experience. And you're right, you really have to do a lot of work before you can earn enough points then convert it to cash. And it's somehow impractical.
I think only the person who develop the apps gets the profit from the ads and those who work on the app does not earn anything.
Most probably. And if someone is in urgent need of money, it's not advisable to turn to 'money-making apps' as a source. It's still better to have a job where you're skills will be paid. It's also more rewarding.