That may be what those specific signs show, but thats not what is important in the screenshot. There may be other signs there as well that are a lot less "reasonable".
What's important in the screenshot is the text because it 1. Acknowledges genjin as a whole has to deal with restrictions 2. Directly states that Tsumiki (a girl with roughly the same dimensions as human) has personal experience with these restrictions and that these frequently stop her from doing what she wants. 3. States that businesses are allowed to create rules that discriminate based on race and personal characteristics.
I donno, this doesn't seem to be that kind of manga. There's an underlying sadness at the realities of differences, but amusement parks are one of the places where laws that say "don't do this if you have these physical characteristics" make a lot of sense. They're safety regulations. We know that as a werewolf, she has incredible physical ability, scaling sheer rocks for fun since she was a child. It makes a lot of sense to me that rather than being held back because she's a wolf girl, she was instead held back because she's a kid.
Rather than apartheid or even legalized discrimination, this seems to be a take on good faith attempts at integration. Differences are highlighted, but rather than being burdens, the manga shows them as strengths. Non-humans are accepted and liked by their peers rather than being distrusted and shunned. People don't look down on genjin, they look up to them and think they're cool. Rather than products being designed to hide or disguise the differences, there's whole lines of mainstream commerce that has adapted to them. Hats with holes for ears, big suits, giant shoes and socks... the school uniform has a skirt with a hole for tails but Ogami likes her tail restraining belt for personal reasons. Invisible dude is allowed to wear a hooded sweatshirt so everyone can see where he's looking. Rather than genjin being smashed into a world that hates them and doesn't consider that they deserve to be there, it seems that the world rather likes their presence and is offering things for them specifically.
That's not what things are like in a society that isn't trying to integrate or is trying to keep the people separate both legally and physically. Genjin are cared for, considered, and even have safety regulations that care about them. Take those warning signs another way; what if there were no warnings for big guys and the ride goes into a tunnel? They could get struck and die. What if there's water splashes involved in a ride and people who change or could dissolve in water aren't warned about it? In a society that didn't care about Genjin, they wouldn't consider them in safety regulations. They shouldn't be in a park in the first place. But instead, every ride has been evaluated with the understanding that there's people who could go on them who aren't just maybe close to 7 feet tall at the most, but 12 or 15. Those are health and safety concerns of non-humans being considered and talked about.
