Doesn't that have to do with the difference in graphics between old RPGs and modern RPGs?
I mean, in the old games it was relatively easy to simply replace the "party" symbol with a "ship" symbol, or whatever...But today?

Pillars of Eternity II lets you sail a ship around on a map view. It has a mini-game where you fight other ships too.

The Evoland games and Chained Echoes have airships.

The Xenoblade games have ridable mechs, but I have to asterisk that with the simple fact that they contain a lot of anime cringe in them.

Off topic, because it's not an RPG, but Aground is all about vehicles. ["Terraria" genre-ish]

In RPGs horses are functionally the same as vehicles, so this restriction is a bit arbitrary.

Divinity 2 gives you a dragon, although technically, you're the dragon, so this might not count, even though it's functionally the same as having a vehicle.

Mass Effect gives you the buggy thing.

Cyberpunk 2077 anyone? Mass Effect: Andromeda maybe? Is a horse considered a vehicle?

I feel like I've seen the same trend but hadn't noticed it as such. The game where it really bugs me is in Risen 2, a pirate game where you don't do anything on the seas.

Mass Effect has the Normandy and the Mako.

Final Fantasy XV has a car.

Wasteland 3 has the Kodiak. I'm not sure what all it can do since I only played some of the beginning of it and never got to that point, but it looks like its main purpose is overworld travel and maybe combat back up?

The Normandy isn't really a good example though because you don't "pilot" the ship at any point in the Mass Effect trilogy. (And the OP said "pilot").

But yeah the Mako from Mass Effect: Legendary Edition is an example.

Jedi: Fallen Order has some moments where you pilot and shoot vehicles in Star Wars. They were short moments from an overall game that seemed a bit long but pretty fun. Not sure if we want to call that an "RPG" but... just throwing that out there. I see "RPG" is a popular tag assigned to that game by users on Steam. I don't really consider it much of an RPG personally though because there is no room for character choice (i.e. roleplaying) in that game. The cutscenes and story all guide you to one conclusion, and the player generally has no options to take things in other directions as they do in REAL rpg games like Star Wars: Knights of the Old Republic or Mass Effect: Legendary Edition.

Another RPG that actually does have a bit more piloting of vehicles is Cyberpunk 2077.

Star Wars: Knights of the Old Republic had some podracing stuff in it, which of course are vehicles that you "pilot." And that game is essentially the King of RPGs imo. But it was sortof a sidequest activity, not a prominent feature of the campaign.

Star Trek: Bridge Crew is a game that does involve roleplaying, in the sense that you pretend to be on a crew of people from the Star Trek universe, taking on a role. And the whole game involves piloting and controlling ships from the Star Trek universe, as you would expect considering it's titled "Bridge Crew." It was pretty fun... I don't remember if you had enough player choice to impact the story/dialog outcomes much (hallmark of a true rpg imo). Some people might say it's not an RPG though because you don't level up, upgrade guns, skills, character ability scores and things like that... but I think those things aren't really what defines an RPG... they're just gameplay features RPGs tend to have.