Why would they? The only reason Tesla dropped prices is because the government capped the subsidy based on sale price, so Tesla dropped just enough to qualify for the subsidy.
We shouldn’t be subsidizing these at all for precisely the reason you stated: we’re largely supply constrained. The EVs that don’t sell well are super unattractive (e.g. Chevy EVs are priced right but have had a ton of recalls, Nissan Leafs didn’t have nearly enough range, etc).
What we should be doing instead is jacking up the cost of fossil fuels based on CO2 load, and do that for imported goods as well (estimate a CO2 load for all products and tax accordingly). It would have a similar effect of making EVs more attractive, but it would hit consumers directly instead of indirectly through an unrelated tax burden. I propose that these tax revenues be paid back to the population in the form of a “stimulus” check with no restrictions as a form of reparation for producing CO2 (or maybe we use it to fix Social Security in the short term). As people move to greener products, the “stimulus” would naturally go down.
But no, we did it in the least productive way possible. Instead of discouraging use of fossil fuels, we’re rewarding companies for increasing profit margins.