A German comedian once pointed out a theory that it reminds people of blood. Having a slight fear of flying in the back of one's head, it may make sense to stock up...

Speaking for myself, I actually like tomato juice a lot (also at home), however, for some reason I need to see it to get the craving...

Yesterday I went shopping in a drink market [Is there such an expression in English? Never found dedicated stores for drinks in the US or UK, not talking about liquor stores] and as I walked past tomato juice I was thinking "Yum - that would be good now!".

Same if I fly LH - I usually spot the Tomato Juice on the cart and have one. Not seeing it on BA, I'll order a coke... weird but true.

As for Bars: I hardly ever 'see' tomato juice in Bars (well for Bloody Marys maybe)... Also it's just not a bar drink, is it?