BossBob you have summed up how the world works perfectly.

The machines are built in the most efficient ways using all kinds of jigs and using preassembled sub units.

Also, in my experience as a field engineer, it can be almost impossible to reach some bits when it comes removing or modifying the sub assemblies.

Manufacturing and Maintenance are paid for from two different pots of money by two different sets of people.

Of course DIY free-manpower changes all the equations anyway, so long winded maintenance procedures aren't so important. FL2 XS SD4 Auto 2010 2012-2017 (21k - 91k miles) (MY2011)
FL2 Metropolis SD4 Auto 2014 2017- (16k - 82k+ miles) (MY2015)
Metro in its 11th Year of (Extended) LR Warranty / Full LR Service History
(Expensive, but Trouble/Worry free - hopefully?)

I just can’t believe the number of times this subject comes up ………Fuel Filters…. !

With the FL2……OE LR boxed or Purflux boxed (same thing) or Coopers ( same thing)…..the rest…..forget them …!!! Not much cheaper & you are bound to have a problem………which may not be easy to diagnose. FL2 SD4 HSE Lux Auto MY 2012— current
D2 TD5 HSE Man MY 1999 470kmls….gone 2014 ….lovely engine..chassis rotten
D1 300TDI Man MY 1996 56kmls….gone 1999…D2 much better
Wife’s FL1 1.8P MY 2001 32kmls …gone 2007…has Mini since.