Hour restriction for 16 year olds?

My state's DOL says that I can't work between 11PM and 5AM **when there is school the next day**... well, it's summer.

Then why do employers say that I can't work past 10PM? Are they trying to play it safe or maybe follow corporate rules?

You can imagine this hour restriction would be inhibiting in certain restaurant environments.

Every employer is free to set their own hiring policies, as long as they don't violate state law. The employer is perfectly within their rights to say you can't work past 10.