First of all Samsung has been so slowly in providing OTA for UI 3.0 & Android 11. They should learn from Apple for the quickness and providing update globally at the same date. Not like Samsung updates are pushed in parts all over and that too with bugs and issues even after so much delay.
From my personal point of view, there is no comparison between apple and Android phones in general. As apple they own the ios whish means there is one line of users which can't delayed the updates. However, other android phones each company has its own UI/Customisation rather than multiple lines of production. Even more, samsung yes has a lot of bugs which is still in normal range for any software in technology world in same time they keep fixing it. By this im meaning that samsung they doing very good job but they still in the highest ranks of phones tech in world
Samsung's software contains numerous characteristics compared to the company that you mentioned especially with Note lineup such as Air command, air action, Bixby routine, Edge panel, Dex mode....etc. Therefore, it's normal that it'll take longer time to test the update, and then approve it.