Wouldn’t it be easier to have stools available that a kid could pull up to the sink to use a normal height sink, than to have sinks that are exclusively useful by kids?

The bathroom argument that you made is akin to saying that folks shouldn’t feel entitled to bike lines / safe sidewalks because our cities were designed for cars and sidewalks and bike lanes are expensive for a tiny percent of the moving population.

Bike lanes are installed by the government using taxpayer funding. Bathrooms (in non-public spaces) are installed by private companies. Difference in expectations there, for sure.