The reason checks are so easy to get revokes (not chargebacks) is that there is no instant clearing for checks like there is with a credit card.

A check number is taken, if it appears valid it is then accepted. At midnight during batch processing they check to see if the funds are available. If the person is lucky enough to have used a non Federal Reserve Banks ABA and a non-Fed Reserve sponsored bank, it'll take a day before the batch return auth number gets back to your processor at which point the subscription should be deleted, and, it is then considered a revoke.

There is no real 'chargeback' per se, but, there is still fraud and oddly, unless you can show intent, I have yet to see an ACH merchant get shut down for too much fraud.