Maybe a sound guy should chime in...
Once upon a time bass amps didn't come with DI's. When they started showing up on amps it was sort of a afterthought. Often didn't have a ground lift, or a pre-post option, and some of them sounded pretty bad. This leads to 30 years later there still being a stigma among some sound engineers that amp DI's are bad, which is mostly no longer true.
The second half of the problem is that yes, some sound guys are lazy. The bass channel is already set to a generic "good" bass sound, and they don't want to have to change anything. This is why you sometimes get that 5 second sound check.
If I'm working with a house sound person and they try to use a whirlwind DI or something I just ask if we can use the one on the amp. I tell them it's a tube pre with a transformer coupled DI, and can we just try it? Not once has it been a problem, you just have to ask nicely.
Now if the guy's an arrogant jerk, there's no point in arguing. Nothing you say will mean anything to him, and your best bet is to not cause a problem and be nice, because if you make the guy mad he'll just turn you down in the mix.