Re: Excuses, excuses
Oh dear. Oh dear! If only it was that easy, smartypants.
a) Taking seats out does not change a passenger plane into a freighter. It does for things like PPE that are light but fit through passenger doors. Freight (as in proper freight) is carried either on pallets or in containers, both of which, surprise surprise, do not fit through the standard passenger door!
b) Freight has not been subsidised by passengers, but around 50% of all air cargo is carried on passenger flights. Why? Because as much as passengers carry up to 84 kilograms of luggage (hold and carry-on) with them, there's still half the plane to spare.
A sum: A Boeing 777 can carry 102 tons of freight and has capacity for a *minimum* of 300 passengers. 300 passengers + 10 crew at 100kg each + 20 kg of hand luggage + 64 kg of hold luggage works out to around 57 tons. That leaves you with another planeful of freight capacity lost to... dead air. So, load 'er up with another 45 tons of *stuff*, and score bigly!
c) Cargo planes have reinforced floors of the main cabin/loading space. Passengers don't weigh all that much. Freight does have a lot more mass, it needs to be tied down to something that can hold on to shifting cargo (well, cargo shouldn't *shift*).
There are airlines who have dedicated cargo arms (Lufthansa, Emirates, Etihad, Cathay Pacific, Eva Air just so mention some well-known ones), and there are dedicated cargo airlines (Kalitta, Cargolux, AirBridgeCargo, Antonov Airlines...). Their planes have been busy nonetheless, but the thing is that *passenger* airlines fly where freight needs to go too, so that kind of point-to-point capacity has... evaporated.
So no, it's not just a case of "remove all the seats and bung a bunch of stuff in the main cabin". There's *a lot* of hard work to make that happen.