Are there big differences in maintenance/care between different types of clipless pedals? I was reading this article http://www.bikeradar.com/us/road/gear/article/best-road-bike-pedals-33045/

and it talks about maintenance/care with a couple of the pedal options, even mentioning that "Shimano" pedals can have mud and dirt in the cleats, and still connect to the pedals fine.

I am curious if there are pedals/cleats that we should avoid as beginners due to them needing to be taken care of frequently, as well as any that we should avoid getting dirt or anything that could "clog" the pedals?

From what I've been reading there are a lot of interesting pedal systems out there, but in most articles it seems that the name "Shimano" keeps coming up as more of a beginner friendly option, even though there are some that sound nicer.
Shimano pedals are usually brought up as a good beginner pedal because they are readily available just about everywhere, have several low-cost options, have standards that much of the industry follow for cleats and cross compatibility, and require little maintenance.  As you said, they don't get clogged up easily, but it can happen.  It just takes a LOT of mud.