Though I accept it's not intentional, this is not a good comparison. The Shimano 4 speed hub gear had nothing like the reliability of their others and as a result was discontinued back in 2005 and has never been replaced.
Since then their hub gears have generally been reliable and are certainly the fastest gear changing ones. The choice model currently in terms of longevity is the Alfine 8 complete setup.
The rival 3, 5 and 7 speed SRAM models are also reliable but have slow gear changing, sometimes embarassingly so, and SRAM are currently engaged in new designs. They had meanwhile introduced a 9 speed model, the i-motion, but that has failed in the market and appears to be withdrawn.
Sturmey Archer folded of course, but the Oriental company Sunrace took over the rights as Sunrace-Sturmey. They introduced one new model, the 8 speed, but that is somewhat eccentric in having bottom gear as a direct drive with all the others higher ratio. That means it has to be used with very small chainrings and large rear sprockets and efficiency is worst in the most often used gears, so once again is a failure in the market.
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Shimano hub gears are not repairable according to Shimano Service Centres. And even if they were they are beyond the resources of your average bike shop. Do you have inside knowledge from Shimano of their planned product lifespans?
Would we accept car gearboxes failing completely after 4 years?
My hub gears were fantastic till they nearly killed me. You can learn how to dismantle them from google, (implying they are serviceable) but you won't find anyone willing to tackle it.
It's amazing that Sturmey made simple gears that lasted for ever and a huge company like Shimano can't. And that's my point surely - they are always advertised as low maintenance and durable, when they are nothing of the sort.