For large sums of money, it’s pretty common to use cashier’s checks, which is probably the kind of check that they’re talking about here.
Aren’t especially for large sums these very risky? I mean you could lose it or they won’t believe it’s real.
Cashiers checks aren’t risky. If the bank they deposit the check at doesn’t think it’s real, they could still deposit it with a check hold.
After that you wait until either the check clears or it gets rejected, and that usually comes with a fee. So banks probably don’t mind the extra fee income