manufacturing costs? shoving a thread on the head tube would mean yet another process and tooling when making the frame with no real benefits, I’ve never had a press fit headset cup come loose yet have any of you?
As for press fit/push fit BBs there are plenty of them to choose from…
“standards” include:
Mid (now quite common on BMX)
spanish
US
BB30
BB92
ISIS Overdrive (I think it was called that – don’t think anyone made a frame for if though)
Press fit BBs make sense all round but as ever there’s too many competing so called standards to stop most MTB frame and component manufatcturers sticking to the established and just about still adequate Euro….
I think Mid would have been great for MTBs but then HT2 MTB chainsets came along with such a stupidly OTT axle diameter and pretty much scuppered that idea..
ce la vie.