More or less the cost is the same. Turbo engine nowadays comes with integrated parts to reduce cost like single exhaust port head. Hence, eliminate the use of exhaust manifold.

It's more like how the manufacturer control warranty claim and complaints which affects their aftermarket cost and reputation, turbo engine wear engine oil faster and if it's not taken care it'll break down in no time.

To prevent that, manufacturer has to install more sensors to force user to take a better care of the car. By all these, manufacturer can push responsibilities and cost to end user to prevent warranty claim.