Yeah perhaps my dial-in skills aren’t up to scratch but even buying a familiar coffee I get enough variance between bags that it takes a shot or two to get it dialled. Not undrinkable, but definitely not dialled.
I’ve had stubborn light roasts where I’ve used half the 250g bag before I’m happy.
Also from the roaster’s point of view I wouldn’t want to be the person bagging 50g doses en masse. I’d imagine cost of labour/packaging/posting for most small/med size operations would not make sample size bags worthwhile.
I do agree though, it’s frustrating when you spend £10+, particularly on the pricey limited single origins that you end up disliking on the first shot. I love to try new coffees but I must admit there’s probably only a handful that I keep going back to over and over. Even fewer that I’ve bought many kg of.