It's not a mistake native speakers would make unintentionally but I absolutely understand the ESL problems and, full disclosure, still have to remind myself about the rules for possessives.
It looks wrong and the system is wrong I will not apologize for or be bound by the failures of dead dudes
A lot of people aren’t native speakers and also this is an easy error to make even for native speakers.
I'm pretty sure non native speakers wouldn't make this mistake.
It's not a mistake native speakers would make unintentionally but I absolutely understand the ESL problems and, full disclosure, still have to remind myself about the rules for possessives.
It looks wrong and the system is wrong I will not apologize for or be bound by the failures of dead dudes