Avoid busses, choose metro/train instead. 
I had the same experience as other reviewers here seem to report.  Entered the bus, took a seat, dropped the bag, and went to check-in (in a matter of seconds, doors were still open). And yet, few moments later, I got fined (despite having the ticket) because the inspector said he had seen me taking the seat before checking in. People around me spoke up to question the inspector (if you´re reading, thank you!), but unfortunately it is true: if you read their rules on the Movia website, it says that check-in must be the first thing you do. And if it is true that inspectors get commissions for fines, then maybe they really fish for these small details. Who knows: I paid right away, for peace of mind! But won´t take busses until they make it possible to check-in before boarding (e.g. at the bus stop or via smartphones). Movia´s loss, cause I have always paid every single bus ride (including this one)!
Note: while I can accept the fine because the rule (for as unrealistic as it may be) says check-in is the first thing you do, I am still uncomfortable with the inspector saying "you checked in just because you saw I was here". That is assuming, profiling, and prejudiced. And unethical. And also: if you entered with me or even before me, how could I "un-see" you? Should have I not checked-in instead just because I had seen you when I entered the bus? I really don´t get it. 
April 5, 2024
Unprompted review