I think most men are so infamously dense because they don't want to misinterpret things. It's a really thin line to walk and falling might ruin a friendship or make things very awkward. Very good manners/kindness and flirtatiousness are very difficult to distinguish.

Making the first move and reading things wrong can really hurt, especially if the other party wants it too. I had a female friend that was very friendly, who'd hug and hold hands with me at times. Friends told me to go for it. When I did she told all of her friends and I was collectively humiliated by the whole school. You could say I dodged a bullet, but it felt like I was by a car.

I'm over it now but I'm now very risk averse. Unless somebody are practically yelling at me to date them, I will only assume friendly intentions