For those horrified with the prospect of sitting next to a stranger, some Chinese airlines offered (and probably still offer) the opportunity to book the adjacent seats at a reduced cost, maybe 50% of the cost of that seat for a fare-paying passenger. This way, the seat is not "wasted" from a commercial standpoint and the customer gets their much-needed peace of mind.
As for the overall concept of social distancing on aircraft - if it's that important to have social distancing everywhere and regardless of masks, sophisticated air conditioning etc, then why is it that I haven't seen many terrestrial vehicles which have had their capacity chopped by a third or more for the sake of it? Why TfL can run packed tube trains with extremely primitive ventilation and certainly no disinfection on each station, but at the same time Ryanair should not be allowed to fly a full aircraft? Can we speak of a "level playing field" when social distancing rules apply to airlines with a huge cost base, but not to bus operators? Surely owning/leasing and running a coach costs cheaper than owning/leasing and running a 737? This is simply discriminatory. Especially in the light of the fact that aircraft have been proven to be far more COVID-safe than many other closed environments.