So, just ask the driver "why so late?" I disagree.
They could call the shop and ask what time the driver left. However, imo it is an issue of cooperation between the shop and the driver. The driver must raise the issue of slow pizza completion and its impact on his tips. If he is the cause he deserves no tip. Either way it is on him.
Well, there really is no laws about tipping, it’s entirely up to you. I do not go to Restaurants that add tips to the check. No way of knowing if the staff actually gets any of it.
Easier than that. Pizza hot? Shop’s fault. Pizza cold/tepid? Driver’s fault.