Permits? YaY or Nay?

Is getting a permit for all the plumbing, including the new water heater in my rental apartment really overkill?

TL:DR - I am having the entire plumbing system, interior and exterior to city pipes, in a basement rental apartment re-piped and installing a new gas water heater to replace the 28 yr old water heater that is there now. I have asked for the entire job to be permited. All of the contractors, handymen, and plumber have said that 'no one here gets permits for this stuff'. It is in a medium sized town in Utah. I just reviewed the new water heater and it is missing an expansion tank. AI tells me there are a number of other features, in addition to the expansion tank, that are required to meet code.

Am I really being overly cautious and 'wasting my time & money' on obtaining permits for these plumbing jobs?