Basically, from what I understand, there are 2 reasons.Why is USPBC considered a 'no-goer'?
Firstly Manchester has a shortage of space for the facility. You have to remember that the gates that are use by USPBC have to operate under a quarantined environment. Under the new MANTP scheme there will only be 2 piers and that would mean a loss of too many contact stands.
Secondly, from what I have been told, the American passport/immigration control at their main airports has become better organised and delays have been reduced - it is over 3 decades since I last flew into America and therefore my experience is rather dated.