Turbo Charging

I have been around turbo charged diesel engines for about 50 years.

Up until recently, their operation was relatively uncomplicated - over boost was handled by a mechanical "wastegate" without any input from the driver. My latest diesel vehicle has almost every aspect of the engine, including the turbo boost pressure,  controlled by the computer. While fuel consumption, power are great and possibly emission reduced, I am not entirely convinced of the benefits of drive by wire.

I assumed the petrol Rotax 914 would operate in the same way but no there would seem to be a computer managing turbo boost.

Why does the 914 require a computer to manage turbo boost, when a simple mechanical wastegate would do that, with much lower level of complexity (& likly cost)?😈