Solid roller lifters...

There is a gap between the side of the roller and the case at the place where the oil passage ends, so the oil can escape there first, thus dumping pressure.
All it's doing is flooding the side of the bush and the roller with oil and that oil is working it's way in from there.. Try doing that with a rod or a main bearing and see how long it lasts.:rolleyes:
If there was a passage along the center of the bearing shaft and up into the bush ( like how a rod bearing or shaft roller rocker worked), then you could call that as purely "pressure fed".
Notice where the oil feed ends? At the top of the shaft, because that's where the maximum clearance is between shaft and the bush for the oil to enter.
As I said, calling it pressurized like a rod or main is not exactly correct.