If your talking about the in depth detail that Stereophile go into when they measure speakers, it's because most don't have that kind of expensive measuring equipment/room, just the basics.
But there are plenty of test facilities around... I can rent an anechoic chamber 10 miles away and I'm in a rural part of England. There must be loads of facilities in the US. Test equipment isn't hard to hire either... If you're speccing a product then you only have to do it once provided you've got decent manufacturing processes.
I think there might be a reluctance because loudspeakers by their nature don't measure well in comparison to the other parts of a hi-fi.