Having a "0" response in the poll doesn't matter because samples taken from voluntary internet polls are useless for deriving inferences about the total population in any case. But having an absolute count of the number of drive units replaced (and the poll shows the very lower bound of the actual number) is helpful in determining the rarity of the fault. That is, if the number of replacements reported in the poll exceeds your own expectation of "rare", then you've learned something. Right now, the replacement of drive units isn't an issue because it is under warranty. But once cars start to exit warranty coverage, the cost and likelihood of such a repair becomes very interesting. The key unknown variable is the "core charge"--how much Tesla credits you for your old drive unit when it is replaced. The labour cost of the repair does not seem excessive. If out-of-warranty replacement is very expensive, expect people to become more tolerant of drive unit noise then they were when the car was under warranty.