I've heard the same thing, that's it's "kinda pulpy". The more I think about it, the less I think it actually matters. If I need them on the ground, or on a ship, then mechanical problems or bad weather or the scene just happening to occur somewhere they stop for fuel can always ground them. If I don't need them on the ground, then it doesn't matter if they go by ship or train or plane. They've gone through all of the short scenarios in the keeper's book, so they know what to expect as far as game play, but I'm having a hard time getting them to get into the role play aspect, so if something like this helps them to be more active and creative, I'm hesitant to say no. I'm trying to get into a less "rules lawyery" mode and say "yes, but..." as often as possible.
And in reality, he's asked for the plane, but I don't know if he's going to try and use them to this extent or not. I'm just thinking through what I may want to do if I was a player, but I roleplay a lot more. His money has the same problem. In the "yes, but.." frame, I would let him say that he knew the original expedition playboy, at least peripherally, and give him an easy "in" to talking to that guy's contacts. That does require him to actually think about what his character's wealth means for his lifestyle and daily routines and such, and I don't think he's up to putting that much thought into it yet. But if he gets into his role enough to do so, I'm going to let him. Or if he decides that he's made all of his money by smuggling, then I'll let him use his smuggling contacts to get his friend's guns in easier and to maybe know of less-well-known networks of refueling spots or something. I still need to read through the rest of the campaign and work out where I need them to hit any given scene without the plane or whatever, so maybe I'll have to backtrack some of this by having some hard-to-find part breaking down, so he has to abandon the plane or something, but we'll see.
I've played DND since 2nd edition, and have been DMing for 10 years now. I got thoroughly burnt out on d20 altogether just due to how constricted it gets, especially at high levels where we'd take 3 hours to run one combat simply because of all of the options all of the monsters and characters have for rolling dice. So I swapped to CoC to get back down to a more basic "theater of the mind" feel and am really liking it (but haven't been able to be a player at all, yet. 😞) But the players are a different story; one has only ever played final fantasy style video games, and the other only played a little dnd under d20 where it was all "roll play" instead of role play. So anything I can do to get them to envision the story from their character's point of view, even if it's a view skewed from what "reality" would be in the situation, I should probably try to go with.
Basically, let them make it their story. After all, it's supposed to be me and them creating a story, and every group should have a different story from every other group anyway, at least slightly. If they don't, then it may be too much on rails. So if they want their story to involve flying around a lot, and that makes it more memorable and fun for them, even when they do eventually get wiped out by doing something stupid, so be it.