Well, that´s the way YOU see it. Perhaps the word "order" is misleading? As I´ve explained before, the RFO was originally a mark of the sovereign´s affection, not an award that had to be earned!
So in that sense giving CPsses Mary or Mette-Marit the order at the wedding was a well fitting thing to do as the 2 monarchs knew their respective daughters-in-law a long time before they married their sons - and obviously held them in pretty high regard.
I would never assume the idea the british Queen would think Catherine should first "earn" it before she gives it out. Her sister Margaret was in her earliest 20s when she received the order and had hardly the chance to deserve it due to her age, but still received it anyway (her 14 ! year old cousin Alexandra of Kent wore 2 RFOs at the Queen´s coronation! A 14 year old schoolgirl had had also hardly the opportunity to work for Queen and Country to earn it, too...)
Besides that, giving the RFO to a lady is often regarded as a tradition, a thing you just do because it has always been that way. We cannot compare ourselves, the way we think and things do (along with the lines "do something for me and then I grant something to you") with how things are being dealt with in a reigning royal house!