Why is removing a spare tire from the trunk so time consuming

So the bolt & thread is still long enough when tires of different sizes are used.

Edit based on comment: Many cars can have different wheel diameter and widths as standard, usually specified when ordering the car and often changed during the life of the car by those owners who wish to.

My own car can come from the factory with 16", 17" or even 18" as standard and iirc 19" can also be fitted.

And as for the spare that is usually one of those space savers limited to 50kmh...