I wouldn't worry about it for typical pet snakes (not giants & normal snake teeth) but I certainly stayed current on my tetanus shots (still do) when I worked
with rattlesnakes. You actually need a DEEP puncture wound for tetanus, like fangs would accomplish...our typical pet snakes would be unlikely sources, IMO.
Tetanus is such a horrible illness & so preventable, I can't fault anyone for their concern though. I've not seen any studies on this regarding snakes, as relatively few people are at risk, but for anyone that works around the yard or nails things, it's a darn good idea anyway.
Also, for captive-bred snakes, where would they even pick it up to "carry it"? Better chance of being hit by lightning...
Tetanus requires a deeper & narrow wound that doesn't drain easily...all of our pet snakes have teeth that leave surface wounds that are "accessible" to clean out.