There appears to be a list of 'sanctioned' apps. I like everything else about the design except this (finger print to show colour is awesome). Why Uber and not

There appears to be a list of 'sanctioned' apps. I like everything else about the design except this (finger print to show colour is awesome). Why Uber and not Lyft? Why Google Maps and not CityMapper? Why spotify and not google play music? Why FB messenger and Whatsapp, why not just one or the other (or neither!). Are the apps actually locked down, or are there just examples? If I end up using a different map tool can I install that one from the play store and use that instead of google maps for example?