Unless Elon offers it for free, they'd start at the bank level, blocking payments. Then they would put pressure on Elon, putting Tesla's ability to sell there at risk. That's before they do anything from a technology standpoint.

Yep, and that's only step 1 on a 100 step ladder. With monitoring tech that they probably already have in place, unless there's a widespread coordinated effort to obscure it (which itself would be extremely difficult), it wouldn't be hard to find the people accessing Starlink and punish them. There are a dozen different angles the government can take to make this impossible without great personal to the participants. I doubt it ever gets that far as the financial restrictions alone will be sufficient