As I said, this is hard for an attacker trying to steal large sums, which is what institutions care about.
The difference is that TLS certificates can be easily revoked if a key gets lost or compromised.
That’s not possible with a co-signing key once it is enshrined into millions of UTXOs. In contrast, with CAT, EXPIRE, and CSFS you can build an infrastructure similar to TLS, including certificate authorities and such.