I think you have it exactly backwards. Do a mental experiment with me. Let's say we have a hurricane here in Colorado and lose power for an extended period. Since Home Depot is not allowed to raise the price of generators, the first few guys lucky enough to get there early buy one, buy a spare, and buy a couple more just in case a friend or in-law might need one. Why not? They're cheap.
Why not? Home Depot will limit quantities to 1 or 2 to prevent scalping. Not sure what things are like in Denver, but in actual huricanne country, this sort of thing is the norm. Home Depot doesn't like scalpers anymore than you and I do. It's bad for business. Customers will remember that you were out of stock when you really needed them, while Lowes was stocked because they blocked scalpers from cleaning out their stock.
If the price was allowed to rise to the point where people only bought what they really needed then more people would be able to get one. By the same token, if generators are going for $10k in Colorado, people all over the US would clean out their local stores and start driving my direction. I end up with power in a day or two. That might well be worth $10k to me. If no one is allowed to raise the price, it's not worth anyone's time to make the effort, and we wait for the government to move. And we wait. And wait. And wait. It could be weeks or months before I have power. Simply put, raising prices is the most efficient way to allocate scarce resources. That someone makes an "unfair" profit is beside the point. It's luck. If you buy a lottery ticket and win, is that unfair? How?
Not sure I follow your argument here. Ignoring a retailer's ability to not sell to scalpers for a minute, I'm not sure how raising the prices at the retail location is an efficient way to allocate resources. You now have people who are opting not to get get the generator (or more essential need) because they would rather risk it than pay twice as much as what a generator would normally cost. Maybe the price will drop if others take the same attitude, so instead of getting essential goods to people, you having to spend time negotiating for a better price. Not the rich folks, they don't care. And what happens when the retailer underestimates what the market value is, and a scalper buys them up. How does a typical customer find out they gotta go to Billy Bob's house to get an overpriced generator. Doesn't sound efficient to me.
To be clear, I'm not talking about normal market supply and demand here, but when an effect causes a drastic change in supply and demand for essential goods.