Do trash cans in residents rooms have to have a lid?

No, they don't need a lid, but if they have one it has to have a foot pedal for opening it. Although a lid traps odors, it also accumulates mold, bacteria and viruses. Personally I do not favor lids. Diapers should go into a diaper bag that is tied closed.

Would be nice if they did. In the meantime, ask for it. If that doesn't work, buy your own.

Probably because if they fall on then, the lid is less harmful than the side of the open edge of the can. Also, keeps things than may be less than hygenic under cover.

I guess it depends on the facility and how they manage the wastebaskets. Is there a certain reason that concerns you that there is no lid?