pkulak said:
I wouldn't worry too much about the receptacle. That part is super east to swap out later if you need to. It's running the wire and getting the breaker set up that's the hard part. Put in what ever receptacle you need for the EVSE you want.
Yes, it's cheap and easy to swap a 14-50 with a 6-50 receptacle. Just turn off the breaker, verify with a voltmeter that it is indeed off, and with a screwdriver and about 5 minutes, you'll be swapped. The receptacles are about $10 each.
I would probably pull a neutral wire with your two hots and ground so that you can install a 14-50, and then just not use the neutral wire when you decide you need a 6-50. For myself, my outdoor 14-50 is wired with neutral so that any EV can charge plus anybody who would visit with a motorhome can also plug in (and motorhomes need that neutral wire). But, my two indoor 50 amp plugs were originally 6-50's, and never had a neutral when I installed 14-50's there.
Yes, Tesla folks love the 14-50 because those cars are real traveling machines that need to go to plentiful RV parks to recharge their cars. When you buy a Tesla UMC, it comes with a 5-15 (120 volt household plug) and a 14-50 plug. If you want a 6-50 (240 volt welders, etc) or 14-30 or 10-30 (dryers), you have to pay $45 extra each.
So, buy whatever EVSE you want, and put the appropriate plug on it (6-50 or 14-50) or swap out the appropriate receptacle on your wall.