I dunno. When someone paints a wall white - I don't think it is necessary to put up a sign that says "white".
Except maybe for blind people - and then it would have to be in braille. But if you only put up THAT sign, then it would be discriminatory for the sighted people - so then you have two signs. Of course, not everyone knows English - so you'll need to put up some more signs that describe the colour in multiple languages. But there are thousands of languages. So you have to limit to only so many. But who decides? Well, you're going to need a committee. How many people are on that committee? And how do you decide who gets on that committee? Well, you're going to need to do a survey of the people to decide that. How are you going to fund that survey? You could get a GoFundMe site. How much do you think you'll need? You want to get enough money - but don't go so big that you don't reach your goal and end up with NO funding. So, it's a tough issue. Maybe something smallish, like $10K would be OK. So, then once you get your funding, you have to choose a survey firm. How ya gonna do that? Are there reviews of that sort of thing? Maybe you do an RFP and choose from the top 5 candidates. What criteria are you going to use? What are you going to do if you select a bid, make an award, and then someone challenges it? You don't have funding to fight that in court. So, now you need another GoFundMe. And on and on it goes. In the meantime, someone organizes a protest against you for painting it WHITE instead of any one of many other colours. Do you have a plan for handling THAT hot mess?
Sometimes - it's just more reasonable to let things stand on their own and allow people to make up their own minds what they'e looking at.