While the TWC SHOULD be cheaper and easier to install, reality is not always the case when it comes to electricians...
A friend of mine is getting their Tesla Model 3 soon, EDD keeps moving but probably end of this month, so just went through this with 14-50 vs Wall Connector. I believe with the timing of his order, car won't come with UMC, so I relayed all the info about how the TWC would probably end up being less cost after all the other parts were included. He also wanted the 14-50 for flexibility in case of another EV, and I told him all about the Jdapter or Lectron adpater to convert Tesla plug to J1772.
But after my saying all of that, the electrician he chose quoted $200 MORE for installing the Wall Connector, though it should be less parts and less work. And while all parts (wiring, outlet, etc) would be included in the 14-50 quote, the Wall Connector quote had a vague caveat about parts not being included. It was unclear he was just saying the Wall Connector itself was not included, or whether he meant the wiring was going to be extra, even though the TWC possibly even has less wiring (due to lack of neutral) than the 14-50. Possibly my friend wasn't specific about amperage, and the electrician thought he needed to upwire it to 80A, instead of the same 50A, even though the Gen3 only goes up to 48A? Or maybe the Gen3 seems to have more complicated wi-fi and provisioning steps, whereas Gen1/Gen2 you just set a dial for amps and that's it?
In any case, my friend didn't want to deal with the extra $200, nor did he want to wait until he had a Wall Connector in hand for the install. So he got the 14-50 installed, I brought over both a Gen1 and Gen2 UMC to test, along with our M3 LR. Confusing because the car is rated to 48A, but the Gen2 UMC is limited to 32A so can't fully exercise the car. And the Gen1 UMC is limited to 40A, which is fine since it's a 14-50, but also can't test to the car's limit.
I then sold my Gen2 UMC to my friend (with 14-50 adapter included) since they're out of stock online. I literally have never used it, and we have the Gen1 UMC already. Which the latter we have also not used since installing a 1st gen Wall Connector, (so there's something to Elon's point about not including it anymore...)