With their own work rules ! Work rules don't change with a union.Unions don't dictate rules or safety.
Negotiated contracts contribute to agreed upon rules. FMCSA (formerly DOT) and OSHA, dictate safety. FedEx skirts these rules often, if the driver/dockworker is willing to submit. Please don't ask for examples, it would take far too much of my free time to cite all the examples we see daily. Even you would likely agree on the safety compliance issues. The skirting of safety rules come from local level, and not so much from the Corp. level. IMHO