We shouldn't forget that "punishment" is a thing of the past in TOS already. Dr. Adams has been working on outdating the practice for 20 years at that point, and even though he subsequently flies high over the cuckoo's nest, his teachings (and his neutralizer equipment!) remain in use. It's never punitive jailing or fines for Feds after that, only therapy to prevent repeat offenses (with apparent 100% success rate).
Starfleet of course still regularly flogs its ablespacemen for reasons of stubborn tradition, but Tom Paris didn't seem to get any special treatment for being an offender in Starfleet employ (no special yellow coveralls, no reference to continuing military status), and his time at the penal colony was probably supposed to be therapeutical, too (no fixed sentence length, but something negotiable and subject to evaluations).
So the contrast between what Burnham gets and what other Trek characters get is artificially high for futuristic in-universe reasons already. Perhaps life sentences and death penalties were quite commonplace until the end of the 2250s? We don't hear much about pre-Discovery sentencing: Dr. Soong probably avoided being drawn and quartered chiefly because his work was so valued, and other offenders were either outside Starfleet's league, or dead by the end of the episode.
Timo Saloniemi