The hard thing isn't the wheel, it's the axle. For that, you need a precision that it's difficult to get without at least bronze tools.
It is also worth pondering why wheel+axle was invented so late even in Eurasia (after bronze alloys were invented and adopted, only around 5.5 kya, many thousands of years after agriculture).
This fact has changed my perspective on how much infrastructure already must exist to enable large wheels that rotate smoothly around an axis. Knowing that, it is no longer shocking that one might make toy wheels, and never scale them up to large ones.
Notable exceptions from the PIE family are semitic languages, and Hungarian, Basque, and Finnish.