@MischievousTomato This is why one builds their own Kernel and goes through the tedious process of dealing with SE Linux. All of those explicit permissions and users who are allowed to access files are very important.
GNU/Linux isn't behind as much as it is divided. There are around four separate MACs that can be used. Beyond the MACs, there's IDS and the hardware security like a TPM. Make no mistake, Linux can be locked down tight. Nothing is truly secure and it's only a matter of time before it's broken.
The true reason why Linux and Mac are seen as more secure is because of their past. They both are Unix Like and Unix had to manage multiple users without dying immediately. Windows wasn't designed for this type of environment and it really became apparent.
Does all the above mean that Linux is better? Not really no. One should stick with what they know best. Apple and pricing make it difficult to say positive things.
Knowing the code one runs is important. A trusted codebase should be reviewed frequently. Even though the biggest problems can be difficult to find, there's no reason not to explore how something works.
It's a journey and not a boot camp. Just try to enjoy the ride and don't try to learn how to harden or trim a Kernel in a day. It's not going to happen.