[dagw]

if the majority of them are for privacy, there is absolutely no reason for them to vote against it

That's not how politics works. Most politicians belong to political parties, and sometimes you have to vote against your personal conviction and with your party, especially if you actually want to get stuff done long term. Compromising by voting with your party and against your convictions on one issue to ensure that you get their support on another issue you consider more important is what politics is all about.