In the US, it is quite illegal to not give any of the tip to the worker. Managers and apps can’t keep any amount of the tip, and the only way it’s legal for the worker to not get the whole thing is if the service uses a tip sharing setup where it goes into a pool that is distributed (in which case it is evenly distributed amongst the participating workers, management still can’t legally take any).
Illegal things happen, but almost certainly not as often on an app that helps records like that than you’d think