If you yank out an SD card on it from a phone that was forgotten behind:
You now have access to all of the potentially unencrypted files on it
Threat actors can replace trusted files with malicious ones to exploit potential vulnerabilities in applications running on the Android device
In 5 seconds you’ve walked away with it, as opposed to a laptop which requires you to physically unscrew it
If you have a phone without an SD card they only have access to the USB port, which is locked with software and in some cases hardware. Removing the SD card slot is one less attack vector, it will make the device more secure one way or another.
Leaving your laptop around someone can also yank the SSD. Modern laptop operating systems generally have the option to encrypt their storage devices.
You can encrypt microSD cards but you must do file transfers through the phone itself through USB which I guess is no different than having an encrypted drive on a laptop. I haven’t looked into how modern SD encryption works on Android.