Totally agree with all the above, thought it was just me!
As an ex-cancer patient I've had a
lot of blood samples and cannulas (I stopped counting after the first few dozen, it's probably 300+ now). The veins in my arms are much smaller than 'normal' and more spread out - it's as if they sent out tributaries wherever they needed more blood flow rather than just making an existing vein bigger. Like
Spireite said they move when struck a glancing blow (but do yield to a direct hit) and are extra-rubbery: both the phlebotomist and I can feel the pop when the needle does go in. Normally nurses can't manage (doctors sometimes can but are usually much rougher - more bruising) so I get sent straight to Phlebotomy instead! Usually they use a butterfly rather than the type with the gathering tube socket directly attached to a needle - this makes it a lot easier, especially with the smaller sizes (normally blue, I think).
I've not had many veins collapse but I do have a couple that are very thrombosed now - one just through overuse and the other because they stabbed the butterfly through a valve

I do point them out to people now so they don't waste too much time. At my last set of bloods they decided on a spot and then partially guided it using the scars

It's a bit of a c**p thing to be expert at but I suppose we have to take what we're given...!
Stone