Totally different type of plastic. Ziplock is Low Density Polyethylene like our Cutting Boards, and our Bucket Liner is Hi-Density Polyethylene. HDPE is like the plastic shopping bags you get at the grocery store. Thin, but very strong. It can hold a gallon of milk with ease, but if you get a puncture, the whole thing blows open. Low Density is like a Hefty Trash Bag, it can hold a lot, & if it get's punctured it will not tear. LDPE is much more expensive.
To use LDPE as a bucket Liner would be overkill and a waste of money. These HDPE bags work fantastic, and with the support of the bucket, you'll be solid.
Having said that, we've put thousands of lbs of meat in these HDPE bags and have yet to have one tear on us. You just have to be careful not to puncture them.
We may come out with a thick ziplock type plastic, but for now we're starting with this.