I see it avail DRM free on Humble. Again on Steam. If it is DRM Free already, why is it not here? I would rather support this site than the other two.

In development since 2013...

I get that. Just why is it not on GoG?

Possible reasons:
1) Because the devs don't want to release it on GOG?
2) Because GOG doesn't want sell a game that's in development for the last 11 years?

Throw a coin.

It's called Rigs of Rods. :P

Also: "its not actually DRM free on humble at all, even though they offer a direct download." is a possibility.

I purchased it through Humble & it's definitely DRM free.

Bacause ins't either a RPG or a Porn game.
[insert diversity and inclusion joke here]

On a more serious tone, forgetting the aversion GOG have towards sports games, it might be that the BeamNg team doesn't want to publish the game on GOG for several reasons, one of them being not wanting to support another build as stated several times by diferent devs. I've just checked and the game feat achievements on Steam and port them to GOG on every build could not justify the increased work.
Let's be honest here, judging by what we see in the forum, the game would not sell that well here.
That said, I'd love to be proven wrong :)

BeamNG.drive is just another contender for the category: "Games that will never be finished".

Like its cousin Project Zomboid.

That one is also in development since 2013, is available as an "inDev" title here on GOG since January 2016 - and is still being sold as "inDev" title to this day - more than eight (8!) years after its GOG release.

Apparently, the last update, that that unfinished business received, was in December 2022.
Strangely enough, nobody here seems to mind...


Edit:
A quote from the Humble Store:
"BeamNG.drive is provided via Steam for Windows and is also DRM-free for Windows .
A free Steam account is required."

It's not the same game, even close. It might had been a few years ago but the amount of content in BeamNG is surreal. Most of the content comes from the integrated mod manager but due the popularity, it has tons! (either metric or imperial)

I've tried a bit of Rigs of Rods a few years ago (on Linux for those who care) and it felt more like a tech demo than a game, or a simulator. The computer requirements are much more easier on Rigs of Rods than BeamNG though Let's hope it will stay in dev for a lot longer, given how the game is designed :)

My vote added. Totally. GoG seems to want to corner or have a monopoly on the smut market instead of bringing good content.