There aren't more and more people "complaining" about selecting services for catering, ground service, the selection works perfectly fine, and if you don't like "selecting", the operator menu has a fairly short timeout, which will automatically select one of the operators automatically so, the system works perfectly.
And the reason why it's WRONG that your airline would guide the operator selection, has been explained not only in the manual, but also so many times, and I think to you as well, many times. I'll try again: the reason why your airline should NOT control the operator selection, it's because the operator is something that is available (or not) on the AIRPORT so, it's correctly related to the airport profile instead.
Because, of course, it would be wrong to expect your favorite operator would follow you everywhere you land, which is what will happen if your own airline controlled the operator.
Since for quite a long time, it's possible to assign any operators to any parking spot, the airport profile can realistically set which operators are available in a certain place so, even if the default scoring system is not accurate for your liking, the explicit operator selection can override it.