I doubt very much slowing down other traffics is a standard practice among IB captains. Probably there is an icehole or two, same as in any other company, but what you are saying I think is over the top.
And ATC giving priority to IB and ANS traffic, I find it hard to believe that it's also an standard practice.
I understand Spanish ATC service can be close to infuriating in some cases but... some of this stuff I think is too much, and I think you keep on blaming the "individual", instead of looking further up.
And I think IB pilots have nothing to do with IB Express.