It does in fact cost $3,000+…
It does in fact cost $3,000+ for a licensed electrician to upgrade an electrical panel. And no, they couldn't just plug in a 220v without upgrading the panel. I think it's reasonable that this particular detail could've been overlooked before buying the car. You can do research, but I don't think most people are going to actually have an electrician come to your house as part of research. Most people would assume that their panel can handle it and it's as simple as running a new wire, as you said.
With that said, most of the cost of upgrading the panel is for skilled labor. His brother is a jerk for not hooking it up with the family special. $1,500-$2,000 easily would've net him $500 profit for the day.