Europeans very very rarely have a natural hair color lighter than an darker "ashy" tone as adults. With the exception of northeastern Europeans where it's reasonably common but still a minority.

Whenever you see a "blonde" white woman it's more likely than not to be dyed.

To understand the true prevalence of naturally light blonde hair in Europeans, ask yourself when was the last time you saw a white man with that hair color? All the white guys I know with blonde hair as kids have had it darken considerably since.