From my perspective, bathrooms with privacy stalls/screens are an issue that can be worked around and was not my concern with Charlotte's ordinance.
Here is a very real, not hypothetical, situation that the Charlotte ordinance allowed.
North Carolina has several large aquatic centers, including one in Charlotte. The primary locker rooms in these facilities are open changing areas. The aquatic centers host numerous swim meets involving kids ages 8-19 or so. Several thousand swimmers use these aquatic centers for meets each year. Particularly for the girls, the tech swim suits they wear for major meets require assistance to put on from other swimmers and is literally a 10-20 minute process that occurs in the open areas. The aquatic centers are also used by the general public and at times have some public lanes available during swim meets. The Charlotte ordinance would have required that their aquatic center allow someone who indicates they identify with the gender that does not match their biological parts to change in the locker room of their identity. I think it can be accepted that would make numerous swimmer uncomfortable and uneasy - not to mention their parents who are not allowed in the locker room with their kids at meets. That question was posed to the swimmers on my daughter's swim team and the solid consensus was they would not be comfortable with a person of the opposite biological sex seeing them and being seen in their open locker rooms.
Now you're left with a dilemma. Either a small number of transgender people feel uncomfortable about not being allowed in the locker room of their identified gender, or a much larger number of people, many children, feel uncomfortable about having the opposite biological gender in the locker room. So who gets priority? In my mind it is pretty clear the large majority do.
I realize most transgender people would not do what the ordinance allowed, to which I would paraphrase the argument I've read here from proponents "If they aren't doing it now, why get so worked up about them being prohibited from doing so?". Wiping out the Charlotte ordinance then prevents what could have occurred with the Charlotte ordinance - the rare transgender who would go change in the open locker room despite the unease of the majority and the voyeur who decides to take advantage of faking being transgender to satisfy their perversion.