Hi, some of my background: My first CAT operating base was one of the 2 proof-of-concept aerodromes for A-SMGCS in the Eurocontrol land, for many years. We never had any SMGCS routes and until now still don't.
Some of the other, much larger airports publish those (called 'lo-visibility taxi routes') but how much of that is linked to actual A-SMGCS or whether it is just another of the tools in the LVO box - I honestly don't know. BTW A-SMGCS here implies ground surveillance radar and ground vehicles equipped with transponders. You can actually see those on FR24 website!
Thus after landing I vacate via one of the LVO designated taxiways. Those would be centreline coded yellow-green, and then ATC tells me where to go. Whether or not that instruction follows a specific line on the dedicated lvp-taxi chart makes no difference. Most certainly I don't care to hear about A-SMGCS and it is neither a common nor required knowledge for our pilots to know what that is.
I have a strong suspicion the difference compared to US is a) that taxi is always under full ATC control b) owing to much smaller numbers, in general our airports are far better equipped.
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Now, about your LHR example, oh dear.
I completely understand what you mean, 100% agree. There will be a plethora of people explaining why that couldn't even happen, and that is all besides the (rather simple and benign) point you just made. Let's enjoy measuring the lengths people will go to misappropriate the content of your message.
Because after that the debate about the box itself and the benefits of having one cannot be avoided. LHR and UK ATS have very high-quality boxes.
I raise you ....
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Ryanair don't operate to LHR, as a loco they never would...