You're both sort-of right :P . Hamer say they don't have a custom shop as such, but the tagline on their website reads:
"We don't have a custom shop. We are a custom shop."
And then again, over the years they've built custom models for the likes of Rick Nielsen, Glenn Tipton, KK Downing, Jeff Watson, Vernon Reid, Jeff Waters... whereas you and I can't specify details if we buy one. So I guess they did have a custom shop of sorts.
It certainly seems to be true that you'll never go into a guitar shop and see six identical Hamers hanging on the wall (mind you, in the UK you'd be lucky to see any six Hamers in one place). They're definitely not mass-produced.