There are always options, even if you don't trust a zoo that they would let you in if you are slightly late. You can't let a hobby that you like beat you in such a way.
The easiest option is one is to be early, which is something I always do if I do not want to miss a specific train or flight. Let's say you want to visit Burgers' Zoo, which is a roughly 2 hour drive. If you plan to arrive half an hour before your time slot starts (which are 30 minute slots). You can then have a delay of 1 hour and still be on time. And let's be honest, a 1 hour delay on 2 hours driving is extremely unlikely and would give you a more than valid excuse to be late and still allowed entry.
The other option only works for zoos like Blijdorp and Artis, where you only have to reserve a time slot at the desk to buy a ticket at the entrance given you have a KMDA annual pass. There you can book 2 consecutive time slots. As you don't pay to reserve these time slots, it gives you extra room to accomodate any delay. For Gaiazoo KMDA annual pass holders don't even have to book any time slot and can just arrive any time. That said when I bought my ticket at the Blijdorp entrance, they didn't even ask to see my time slot and just helped me anyway.
When combining this and all the other factors that have come up in the pas two years, I think I have unfortunately already been beaten.
I am trying to see options, but I see serious problems with every possible option.
If these time slots were one hour I wouldn't be complaining as much. But 30 minute time slots are just too narrow if you have to travel about 2.5 hours (i.e. Burgers), about 1.5 hours (GaiaZoo) or about 2 hours (Blijdorp), and even if you leave early, circumstances during the travel could easily push you out of that time slot. I would actually consider a delay of up to an hour to be quite likely if something like an accident, a police checkpoint or weather circumstances like thick fog were to happen.
Also even when leaving early the time slot business would give me added stress. Right now that added stress is something I just cannot have, as it would seriously impede the chance of a pleasurable visit and
de facto makes it impossible to even consider one at this time. And especially for the parks that require longer travel, leaving extra early might just not be feasible. And if you were to arrive early, who says they could not make a problem about that also?
As far as I understanding things, there are no valid excuses that will be accepted or even considered, especially on busier days like during the weekend. And you could just happen to have a particularly strict, unfriendly or grumpy member of staff in front of you to make the decision whether you can enter or not. The responsibility falls squarely on visitors to ensure they arrive on time and arriving outside of a time slot will almost always and automatically result in refusal of entry. Legally they could perfectly refuse you entry for being even one second outside of your time slot.
Some parks might accept a later arrive if you are able to give notice, but we would be unable to do so as our phones do not allow us to make other than emergency services calls once across the Dutch border.
I have not seen the information on the KMDA pass holders anywhere and I cannot find it either, so I think that part is incorrect as there is no official confirmation for it. As far as I understand it pass holders of other zoos fall under the same rules as other day visitors and are required to arrive within a time slot, or will be refused entry.
