The proof is there. But if I point it out you'll explain it away as circumstantial evidence and then claim it's not proof.
TOS "The Day of The Dove"
and they do it a bunch of times in discovery.
Cloaking technology was considered "theoretical" by Spock in "Balance of Terror", yet we saw Archer encounter species with such technology from the very first episode, and eventually the Romulans a season later. Which therefore retcons the notion of cloaking being new in the 23rd century no longer valid.
Mudd acting like the technology doesn't exist to catch the enteprise (spore drive)
Likely because spore drives are not in service by "I, Mudd". Have you considered that?