Cars are a little trickier. It's a bigger investment. There's more risk associated with a car. If you live in a place that requires seasonal tire changes, you have to get new wheels and tires with a new car and that's not a trivial thing. You might have to get a new rack to put on top or a new towing set up for your trailer or boat. These are not cheap things. One is inclined to be conservative. However reluctant one might have been to be the first person they knew to buy a particular small electronic, one is probably way more reluctant to buy the first model year of a new car. You sort of want someone else to deal with all the early problems.
Typical consumers don't buy planes, so the decision making process is clearly different. Fundamentally, most planes are bought like apartments or hotels: the intention is to rent out space in them. Capacity utilization is pretty important, especially when fuel is expensive. And planes are incredibly expensive. Once you have one, you usually would prefer to keep running it, rather than buy a new one, even if the new one would get better fuel economy, or people might like the lie flat seats better.
As much as I am tempted to believe that innovation doesn't occur in a lot of automobile manufacturers, they really do try (even American car makers). It can be hard to remember, when we are demanding the car interact well with our media player or computer or phone or whatever, that the car maker designed that car before that media existed or that phone OS had been widespread, etc. Presumably, if iOS and Android and so forth stabilize over a long enough period of time (or, heck, now that USB has become enough of a standard), we can expect more cars to play nice with our gadgets. Expecting airplanes to play nice with our gadgets actually seems like an unbelievably huge lift.
Except it shouldn't be. While fuel has gotten cheaper, it is still not _that_ cheap, and it probably won't stay super cheap forever, and even if it did, there would still be all those carbon regulatory regimes in various parts of the world motivating companies to try to reduce their fuel expenditures. And in flight entertainment systems are hideously heavy and expensive.
So what does it look like to replace them with BYOD? How do you make an airplane -- which will be in service in the configuration it ships it for 5 or more years -- play nice with devices now in the United States, devices now in Asia, devices now in Europe, devices 5 years from now in all of the above, blah, blah, bleeping blah? The obvious answer is: supply data connectivity (wifi) and power. But even supplying power is going to be tricky, at least on transoceanic flights (do you supply adapters? Multiple outlets?). Data connectivity could be intranet (to let people stream airline licensed movies to their devices from an onboard intranet, and maybe let them chat and play games with other people on that intranet), ground-to-air connection to terrestrial internet, or one of several satellite internet connections. Airlines like United seem to be doing All Of the Above. Others are picking and choosing. I have no idea what criteria they _are_ using to pick, never mind what they should be using.
Ground based internet tells us that whatever bandwidth you provide, in short order, people will be complaining that it is too slow, and all those Netflix streaming people are hogging it but don't want to be deprioritized, and you know other cities/countries/continents have much faster broadband EVERYWHERE so why can't we? Ground based internet also tells us that even after a large enough chunk of your telephony customers cut the cord so you can't make any money on PSTN, there will be a bunch of The Olds insisting that you keep providing it and restoring it after damage and threatening you with regulatory punishment if you don't.
So an airplane that provides you with a power outlet configured for the country of your departure's power system and wifi that connects to terrestrial internet is going to have to deal with things like How Come My Tablet Won't Connect and Where Is the TV and I Didn't Bring a Tablet How Do I Watch the Movie?
I foresee job security for the cabin crew. Oh, and I foresee job openings for IT pros in the sky.