They're probably using it because it does kind of fit all the bright colors they use in the commercial. Not the actual words of the song so much, but for people who dont speak French (I dont), it does sound like it's a happy song. Bright colors tend to make people happy, and so does shopping. (so does eating...not sure if eating larks would make me happy tho.)

and if you use the English version of the song, it's just a love song. (different words, set to the same melody, technically not the same song)

"If you love me, tell me that you love me.
If you don't, please tell me that you do.
If you love me, tell me that you love me.
If you don't, please tell me that you do.
Do do do, love me true
Oh oh oh oh "