That seems to be a classic no-argument-no-evidence assertion. And you really need an argument for this one, because otherwise it requires disbelieving in supply and demand curves. If you concede the price goes up, you have to concede that the seller thinks they're going to have less customers. Ie, that people will indeed choose not to buy the thing if the price goes up even a little bit. Otherwise they would already have raised the price because it would be free money for them to do that.

And it is the case that people don't tend to save, ie, they spend everything they earn. In that environment if a price changes, even a little bit, they're going to have to do without something. The maths is pretty easy. I mean maybe they're going to eat less food or whatever because they bought an air conditioning, but there will be people who are literally facing that choice and choose food over comfort. Someone actually has to be quite wealthy before the price of something going up a little bit doesn't force them to make changes to their lifestyle. For some people on the margins that change will be the difference between having and not having air conditioning.

If you want to make an argument that the cost to the seller is small enough that the price won't go up then sure, that might be so. In fact it does happen sometimes. But the people in the thread aren't complaining about small hypothetical fees, you bought that up yourself. They're complaining about regulations that cause the price of air conditioning to go up and chemotaxis had quite a long list that, practically, will cause that to happen.