The Americans conducted a study into Low Flying in the Late 70's and (quite rightly) concluded that the expense of conducting Low Flying traing didn't justify the means.
Its cheaper to accept the loss of a few aircraft and crews than to train everyone with a skill which quite frankly doesn't work.
Low Flying is good fun. Thats it. There is no operational benefit from whazzing around at 50' (100').
The concept that we fly low to fly under radar beams is frankly tosh. Modern radars can see you manning up never mind low flying. Flying low puts you inside the threat band of many SA's and SAM's as well as placing you in a difficult and dangerous position.