Windows, macOS and a ton of other Linux distros do that as well.

First of all, windows and macOS are not for free. They cost extra money, sometimes hidden in the PC cost when pre-installed. When they do a major update, like Win10 to 11, you are at their mercy, if your license can be used to upgrade. Often it can, but sometimes your PC is not "Windows 11 ready" or so and then you get updates for your old system for a few more years until they drop you like a hot potato and throw you to the malware wolves.

Additionally, in Windows the automatic updates are just for the OS itself and some apps from its store. A few apps like Chrome and FF install their own extra update service on top. A lot of other programs check for updates individually or some not at all and often you have to download and run their installer for every update. Idk how it is in macOS tho. Haven't used it in years.

Yes, a ton of other Linux distros also have background unattended-upgrade or similar. However, the people who choose Ubuntu over those are usually looking for a quick solution that almost always just installs without problems. They usyally don't have time or patience for any complications, however small. So they choose the fire-and-forget Linux and additionally have greater chances to find a fix or help in the super rare case it doesn't work, because the bigger user base increases the likelyhood someone else is familiar or has infos regarding that exotic issue.