@ Chemists about plastic bags and Los Angeles recent ban

Can't they just engineer a plastic bag that breaks up in the ocean faster?

How hard would that be to accomplish? We use material science all the time, and even arranging materials more crudely can yield large differences in performance. Tissue is designed to break up fast in water, paper towels are woven to hold together longer, even while wet.

The entire rationale behind banning plastic bags is that they stick around in the ocean for a long time and potentially cause harm, so wouldn't a better solution than banning the bags just be to engineer them to break down in say, a weeks time submerged in water? And of course make sure the byproducts do not harm the ocean when they do break down.

I was at a store a couple of days ago and I saw this guy carrying a stack full of food just to avoid paying 10 cents for a crappy paper bag. What will dog owners use to pick up their dogs droppings? There MUST be a better solution than an outright ban.