I wasn't implying you were dumb. In manual hvac the temperature knob directly controls the temp of the air so some people think the digital temp works the same way. It's an easy mistake.
To your point, if the ambient air temp in the vehicle is 60 or 90 then yes, you would get the same temp from the hvac at both 73 and 83 because in both cases it would be trying to heat or cool the vehicle to the set temperature. The fact that it blows the same doesn't necessarily mean that it's not working properly. If the ambient temp in the vehicle is 78 and you still get the same temp from the hvac on both 73 and 83 then that's a problem.
Ignore Hi and Lo since those are overrides. If the hvac is set higher than the ambient temp you should get hot air. If it's set lower you should get cold air. If that's not working then that's what you need to show the dealer, not just that it blows the same at 73 and 83.