DAC cables are cheating because due to the extremely short range limits (5m, 7m if you're very lucky) they can just put the 10Gbase-R/SFI signal straight on a pair of Copper at 10.3125 Gbaud.

10Gbase-T, to try to get to 100m, throws FEC on it and converts the signal to 4x PAM-16/THP at 800 Mbd, and then uses 4 copper pairs *bidirectionally*. That's the analog magic.