It is probably just legal, but....
This discussion seems to be going round the same old arguments again and again. Wingly, and the other ride sharing sites, are simply a medium through which people can arrange to share flights and, so long as those flights themselves are legal, there is nothing wrong with that.
To be clear, as a matter of law:
1. Genuine cost sharing as defined by both the CAA and EASA (but not the FAA, who accept cost sharing but not these websites) is completely legitimate regardless of the medium by which it is arranged. For that reason, I see no reason for any airfield to ban genuine cost sharing flights of this type.
2. Running a taxi or other commercial service without the necessary licence and insurance is not legal, again regardless of how it was arranged; and if I was running an airfield, I’d ban flights of that type as well.
I honestly don’t understand why it is necessary, or even desirable, to try to ban all genuine cost sharing just because some people abuse the system. You might as well ban all cross-border GA flights because some people use them to smuggle in drugs. Surely the answer is to target the abusers and not the genuine cost sharers?
Edit: as I said in an earlier post, there is also no reason why the authorities can not also take action agains a site such as Wingly if they knowingly facilitate illegal activity.
BTW:I have no personal dog in this fight, because I have an FAA licence and therefore can’t use these sites myself. If I could, I would happily do so. Legally!