I’ve never seen anything else than just Ubuntu or customized Ubuntu preinstalled on laptops.

Endless OS sounds like an actually good distribution, though. It’s based on Debian, it’s immutable, they publish their software as FOSS and they submit upstream patches.

The UI (which is a modified Gnome desktop) looks beginner friendly and easy to use.

Because every OS they ship with they need to support. Lenovo already has a viable, cost effective, support model for endlessos because they ship and support it for educational customers.

It’s not commercially viable for them support other OS that there is near no demand for relative to their overall sales.

Never trust the OS that ships with a device. Wipe it, format the disk, and pray that they don't have a backdoor at the bios level.

To my knowledge the few laptops from the more famous brands I saw being released with Linux out of the box were coming with Ubuntu, can you make a few more examples?

Also Endless OS isn't really unknown, it's just that it's not suggested at all in most communities because its focus is more on making a kid friendly distribution, which is amazing, but it's not really what most people will be looking for

If it's based on Debian then 90% of guides online will work with it anyway

I haven't seen anything that isn't Ubuntu or Fedora

Where do you see this??

My uneducated guess is that Endless OS pays manufacturers to have their OS installed as it has what appears to be privacy-conscious telemetry. It won't be anywhere close to what Microsoft/Apple, but in the Linux telemetry world of the blind, the one-eyed man is king, and so it'll still have valuable data.

Some of the areas that are unlike most other distros I've come across:

• Their website for Endless OS does a lot of tracking and has a policy that is more 'business-orientated' than many distros
• Privacy policy for the OS is not available online, only when downloading program
• They use dark patterns to have the default for telemetry as 'opt-in' which might be the opposite for FOSS IIRC
• Complete list of things tracked here

To me, it's akin to the free third party apps that come packaged with many Android mobile devices. Less intrusive since it's anonymized, but also feels more intrusive because it's the entire OS being monitored. I believe I came across a headline that Fedora is attempting to use the same tracking software in the link above

This review shares a more judgmental view of their practices

This article has a more positive spin

Most of the Laptops I see with Linux are Ubuntu, some Ubuntu based distro like Tuxedo, Pop_OS, or Linux mint, and very Rarely Fedora (I'm not sure, but I think I saw one ship with Fedora).

It makes sense for a hardware vendor to have their own distro. That's the only way they can make sure that everything works seamlessly. Just think, if you put Ubuntu on your laptops and then Canonical do something that breaks your compatibility. It would be a major support nightmare.

As other comments have pointed out, I'm not convinced the premise of your question is correct. I'll throw in Slimbook to increase the sample size:

Probably support purposes but really anyone that uses Linux will just install their favorite distro right away.

~~I use arch btw...~~

like lenovo with endlessos

Wait, when did this happen?

I know that some manufacturers ship QubesOS, those are intended for people with high threat models afaik.

Ubuntu is highly commercialized and trademarked so vendors that offer it make deals with canonical. Dell, Lenovo, and System76 have all offered Ubuntu in the past.

One thing that vendors do sometimes is they offer an official image that includes drivers for that particular laptop and they never make it into mainline. I think that's part of the draw for offering your own weird OS - you basically get to control hardware support and your own release cycle.

Control has other benefits as well. You get to do some branding, which bean counters love, so you get to deliver "the Lenovo experience" or whatever. I think System76 actually cared about this for good reasons and that's why Pop!OS (terrible name) is actually pretty good. Ubuntu kept screwing up their offering so they just did their own thing instead.

Lenovo probably just doesn't want to pay Canonical for Ubuntu certification, which charge per unit fee.