Probably because all of them are dysfunctional garbage, an awful gimmick that crippled the Wii's potential. The only sane one in that era was Sony, since they never really forced motion controls down peoples' throats.
I wish you could use a Classic Controller, but sadly that was never a universal secondary option for those who couldn't get the godawful motion controls to work.
Ergo, more proof of Nintendo's idiotic design decisions during that generation.
I ran into the same problem earlier. I went to play Wii Sports Resort and only found my non-Motion Plus enabled controllers. I couldn't even find one of my Motion Plus attachments. I ended up just playing the regular Wii Sports.
It is really a "Mystery" to me...now I have searched near an Hour...from 4 Controllers -> one appeared.......and of course with empty Battery...so next Search -> Charging Station...