Bleach is used in the restaurant industry to sanitize (everything - containers, utensils, plates, eating surfaces, etc) and it is safe. It doesn't take much (1 capful to 5 gal), and it doesn't take weeks. $6 a bucket isn't much and I'd get those in a heartbeat, but I have a restaurant and go through plenty of buckets that it makes no sense to throw all those away if there is a chance to recycle. I gladly give any away to those that ask, so I assume other restaurants would too.
On a lighter note, we once saw a picture of a guy in the local paper that got arrested for growing pot and in the background were a lot of pickle buckets with plants they confiscated... we recognized the guy as the guy that came around weekly to collect our empty pickle buckets! LOL.