Instead of supplying a mega corp with some free information to increase their monopoly on directions, maybe you could have just mentioned to the hospital staff that they could do with a new sign pointing to the door?
I think the point of having the online map accurate is so people can plan better ahead of time. We had this exact situation recently when my MIL needed to go to get CT scan in a hospital campus but my wife wanted to plan ahead which of the many entrances she should drop her off at. The actual hospital web site is a labrynth of the type that government bureaucracies excel at.
Most of the the you see actual staff in a big organization, like hospital or government office etc do not have authority to add or remove signage. Most of the time its somebody in admin, or even a totally different department in case of government offices (to keep all locations similar) who is actually responsible. That doesn't mean that one should not give feedback, I do, & at least half of the the time it makes a difference.
I tried to look at it that way, but... it only helps other people until Google decides to drop that particular feature, after which all your work is gone forever.
I found the "Emergency" door of a local hospital hard to find IRL, so I added a photo of it from the driveway POV. Another sort of real person you can help are the web-clueless owners of local small businesses.