It frustrates me that people continually carry on bags that are to big. My solution at the gate would be to have people like Dave, be forced to step aside and wait until all the passengers in compliance with luggage requirements board. They can the risk missing the flight.
Follow the rules and you will not have a problem. The desire to “cheat” seems to apply to often to those who want to brag about traveling with carryon only, but want a full size bag.
If you travel on a discount airline, expect to be charged when you decide to try and not follow the rules.
This may seem harsh, but the delays are frustrating when people push around unpaid ground staff