In these situations, the main weapon is knowledge. If the law says you have to give people X number of minutes as break, a union rep's job could be to collect records of when that rule was broken. Then you can hold that knowledge over the head of the employers, who often rely on information asymmetry to get away with shit.

It's not ideal, and certainly no UAW, but it's much better than unchecked abuses. You can use funds to buy appropriate equipment like gloves for workers and for their replacement when they fall apart.