I understand that it is hard on different levels for providers too. But then most times you do not know a provider very well when you start.
A little bit of monitoring is essential because not all of them out there are good. They promise something and do something.In any case, it is to check if your child is coping...even if you trust the provider.
It is true the child shows signs but a child also reacts differently when you start in a new place ..it is sometimes hard to tease out what is wrong.

Trust comes with communication and time ...I do not think parents should constantly drop in but it might be important to do that in the initial times...have to keep it short.

I guess if the provider is not ok with this, then its up to the parents whether they want to go with the provider or not.