Previously I believe only some of the combat robots dealt electric-type damage, so it made sense that it would be the only damage not resisted by snappers since you could only deal it manually by the player up close. However now with the Tesla turrets, should the snappers perhaps also get some amount of electric damage resistance, so that Tesla turrets aren't too strong against them?

Especially since they are already fairly slow, so the slowdown effect of Tesla turrets should already be quite effective against them, IE even without taking greater damage from Tesla turrets, the slowdown would make them quite likely to get killed by other damage sources before reaching your walls with their low base speed.