Logic, the law of supply and demand, and the examples I can observe point to this not being true.
There are two used Tesla on their website I can see in inventory for my area.
1. 2021 MY AWd LR, 39k miles, white paint, black interior, 20 inch wheels, 45,900 price. Same car new - 54,130 (including destination fee). Also sales tax will be higher on the more expensive new one.
Tax rebate is not part of the price and not everyone qualifies for a rebate. However it’s worth noting used EVs can still qualify for 4k federal rebate (up to 7500 new).
2. 2021 MY AWD, deep blue paint, black/white interior, 19 inch wheels, 25k miles, enhanced autopilot, 52,100.
Same car new - 60,130.
So those are $8k+ more new, plus the added sales tax. You might save more on federal taxes with a new one, but the used ones are definitely cheaper. And part of the incremental federal rebate would be offset by higher state sales tax.
Again you need to compare the exact same car and specs, including colors, options, destination fee, etc. If so I guarantee the vast majority of time used is cheaper than new.
It would be impossible to support a market of cheaper new ones/ more expensive used when there is no wait list and people would prefer new to older/used.
Having said that, the used ones are not much of a bargain considering how modest the discount is.