@Jan *****************
you are posting the exact same screenshot which again confirms my point. It's required for the application.
The reason visa exempt entries require proof of onward travel is that there is no previous stage at which it could be required. Before people could travel visa exempt, everyone had to go to an embassy to get entry permission. That's where requirements were checked. Immigrations then only had to check whether you had a visa, as this implied the traveler satisfies anything that you show in that screenshot. Only when travelers received the opportunity to travel visa exempt, some additional requirements had to be formulated for entering. The embassy by the way has discretionary rights to grant or not grant visas, which is another reason it's not additionally required for entry as well: an embassy may be ok with particular travelers going without onward travel pre-arranged.
I don't understand why this is all so hard to understand for everyone here. Although not universal, it's fairly common also for other countries that visas are considered sufficient evidence to be eligible for entry. Sometimes additional evidence is tied to entering, for instance Myanmar requires proof of onward travel for entry if you have a tourist visa. But then they'll write this on your visa so you know it's not (yet) granting entry permission, it's only part of that. There are probably more examples where countries do this but we can't say it's common. The standard is that visas allow entry and requirements are checked by an embassy or similar body. (Myanmar's approach is of course much more sensible than what basically all other countries do: first decide if someone is welcome to enter and then allow him to book flights next, not before. But it's (unfortunately) not at all common.)