"Employees are trusting founders not to screw them over."
So on the one hand, every relationship of this kind (and of most kinds) requires trust.
On the other hand, you as an employee really shouldn't just be flat-out trusting your employers about things where you are technically at odds with them. Even if they have no intention of screwing you over, it's not always about them - they may be replaced by new management as the company grows, for one. Or they simply might not know something, for another - what if they're unaware of a certain tax implication around an equity grant, for example? Founders are oftentimes doing this for the first time, and just like most employees, don't necessarily know everything.
You should really make sure you are aware of all issues and implications of the contracts you get into, as much as is feasible.