As mentioned by others, a level 3 activity permit isn't only used for biking. The card is simple, pop it in your pocket & you're done whether you're riding, walking your dog, paragliding, climbing etc
The real issue is that renewals should be possible online. However that would require a card that didn't expire, which would likewise require an electronic device to check it's current status.
Having said that, an easy solution nowadays would be for each card to have a QR code which could be scanned by any mobile device linking to a basic web form displaying basic card status (active/expired)....of course that still would require sanparks to issue all rangers with smartphones. Plus there's the connectivity issues in parts of the park...
In the end, sanparks is a government institution. Any solution they implement is going to be implemented via a tender process & picked on criteria not at all linked to actual service delivery.