As far as I can tell, all they do is simply limit supply. I'd seriously consider loading up a 53 foot trailer full of generators and drive them 2000 miles to Florida some years if it were legal to sell them at 2-3x retail. But it's not, so I don't bother as it's not worth my time and immense financial risk.
And I'm not even in the generator selling business. Someone who is I imagine could be quite incentivized to keep the factory open a few more shifts and ship a bit more if profits were there to offset the additional expense and risk.
Instead we have these laws that encourage stuff like a single dude living alone buying 3 cases of water at the gas station and the family of 6 who arrives an hour later can't get a single bottle. Or the dual with dual tanks in his pickup truck filling both up and the folks who come by in their Civic needing 1.5gal to evacuate can't.
The response of course to my complaints is rationing, which of course brings up a whole other giant can of worms.
What if the single dude has 1000$ and the family has 10$? The single dude can obviously just buy all the water and the family still gets none.
If you were really willing do to this, could you be so kind as to share your prognostication for where future disaster will strike with disaster planners? For you see, that task would require you at least 5 days of advance planning (assuming you were a champ at locating and ultimately selling them), probably more than a week in any actual executable plan. Even for well-forecast hurricanes, that is pushing it for advance notice.
If it were possible to increase supply sufficiently AND the markets were perfectly efficient (and cows were spherical), price controls wouldn’t be necessary - but these controls were typically introduced after disasters where people died because other people were jacking up prices to levels most couldn’t afford.
Even if it truly is possible to increase supply you may nevertheless have price increases because disasters induce demand and encourage hoarding. The solution here IMO would be to cap prices but subsidize them in order to incentive suppliers to increase supply.
The "pro price gouging" faction just points out that caps provide even worse market incentives for increasing supply and lowering prices than allowing arbitrary and free pricing (i.e, "gouging").