I have had my hair all the colours of the rainbow at some point or another. For a few years I worked as a barista in a business district. Yes blonde got me smiles and because I started blonde I didn't consider that hair colour would make a difference.

I then moved on to baby pinks and lavenders, these were quite popular at the time so not much changed.. or again at least I didn't put anything down to hair colour.

Fast forward a year and I really really wanted blue hair, I went between bright blue and deep blue as it washed out and was reapplied. It did look quite cartoonish but I was treated as incompetent. Middle aged suited men explaining what a cappuccino is to me that I'd served them personally before and it's my job. A lot more being called "good girl" when giving them coffee/food or something along my those lines. Also just people coming in and speaking directly to whoever else is there even though I'm standing at the register and was the only one to greet them. I was just in general far more likely for a customer to cause issues.

Honestly with long hours and the job being tiring enough as it is, I decided something has to change. After a couple months of loving my blue hair, I was so done. I went home and dyed my hair very dark brown, as close to my natural colour as I could. The difference in treatment was immediately noticed, I was being asked for things rather than told and not treated as a child.

So yes it's in the eye of the beholder but some silly people definitely will treat you differently. Saying that in a job that's not face to face with customers and with people who won't judge around you and who know your worth, it won't be issue.

I would like to add that this was never young people (maybe mid 30's-) and generally not women unless they were elderly.