Lateral acceleration is less pleasant for passengers. You don’t want peoples drinks to fall off their tray tables for example.

That said there is a fair about of wiggle room so I doubt it’s a significant issue in practice.

Maybe they could try inventing a way of keeping drinks from spilling when the container is tipped over...

I even have a cool name word to describe it: "lid"!

μg coffee cup https://science.nasa.gov/science-news/science-at-nasa/2013/1...

Lid or no lid, it’s still a problem if your drink falls off the tray table. Which is one of the reasons they say to put your tray tables in upright an locked position.

But even beyond that feeling like you’re falling out of your seat is unpleasant.

Automakers solved this problem many years ago, by making cupholders that are deeply recessed instead of thinking that cups wills somehow magically stay in place with a very minimal indentation (see the "cup holders" on the backsides of glove compartments in 1970s American cars).

Airlines would rather have more people in economy than to include cup holders.

You do sometimes see cup holders on private airplanes, but in commercial aviation the efficient solution is to avoid needing them.

Adding decent cupholders to cars didn't make cars bigger.

Similarly, adding decent cupholders to airplanes is not going to reduce passenger space.

Commercial aviation could stick as many as 850 passengers on an A380-800 in it’s maximum configuration, but the most an airline actually gets is 538 because of business and first class passengers having more room. Increasing passenger space by even 1 inch or just a pound of weight per seat makes a real difference.

Better cupholders do not decrease space at all. Some (better) airlines even have them: they flip down from the seatback. They literally take no space at all. This is ridiculous.

Try really should just cut a sized a hole in the back edge of the tray tables.

People falling over is more of a concern, it would take significant lateral acceleration before drinks fell it’s just easy to visualize.

As to why no cup holders, people aren’t going to use them most of the time and they don’t even help that much in turbulence.