People - Is it not reasonable for supervisors to expect me to be on time for work every day disagree

It is very reasonable for a supervisor to expect you to be on time normally, that's a part of a job. And if you're going to be later (which should be rare) you better let them know.

Reasonableness has nothing to do with it. You are given your work hour parameters when you begin a job. The expectation is that the employee will be at the work site between those hours working and producing some type of product whether its digging a ditch or creating a computer document and for doing so the employer will pay the employee for those hours.

It is up to the employer if payment is made for the time the employee is not there or if continued employment is given if the employee is continually not there during the given hours.