> At any rate, courts are required to accept legal tender

Assuming you’re talking about the US here: there is no such requirement, at least not at the federal level. Individual states may have their own laws, but see for example this notice [0] from a Texas federal court that they will no longer accept cash as of May 21, 2021.

[0] https://www.txnb.uscourts.gov/news/notice-court-will-no-long...