Also, the fact that Coinbase is in the US legal jurisdiction gives its clients confidence they would be made whole if anything untoward were to happen.
If the untoward event is solely in USD, perhaps, but not if it's in crypto. Exit scams, hacks, rogue employees, etc, could still hit a US exchanges' crypto holdings and the government probably cannot or will not compell a roll back, supply expansion, etc, on a major blockchain.
If anything is actually protecting clients against crypto theft, it's the exchange's privately-purchased insurance rather than the government. Although I wouldn't rely on that for much either as insurers are rarely eager to pay out.