I have a car whose spark plugs are a pain in the ass to change. You have to disconnect a number of things^[1], unbolt the engine, and lift it to get to them^[2][3]. The thing is this is a modding friendly car, most everything is easily accessible and user serviceable.
So why are the spark plugs so hard to get to? I doubt it had anything to do with hostility towards repairability because this car is easily repairable. This came down to the design requirements for the car and particularly the engine they wanted to use to satisfy those design requirements.
Long gone are the days when you could sit in an engine bay to work on it because there was that much free room. Modern vehicles have to comply with many regulations, e.g. emissions and safety, whilst simultaneously meeting consumer demands at a price point people will accept. Without knowing the exact model of car you have, I'd say your shift solenoid problem almost certainly comes down to component sourcing - the manufacturer either uses this transmission in a number of vehicles or it's procured from someone else - and manufacturability/supply chain optimization - it's easier to integrate an already integrated solution^[4]. There might also be other considerations such as space availability, weight distribution (since you said you had to pull the engine to get to it), environmental, and efficiency. Again I don't know your exact vehicle, but engineering is a ton of trade-offs and sometimes the trade-offs suck in a particular case while overall satisfying the design constraints.
By the way I agree that German cars suck to work on, but that has largely been the case for every German car I've personally worked on going back to the 80s.
I am 100% certain there are decisions made during the design of various products which are solely or partially predicated on the inability for the end user to repair the product. I also know from first hand experience that many products never have some Machiavellian product manager who dictates designs expressly to be unrepairable; rather due to consumer demands, economics, regulatory and safety compliance, etc the end result is a product that is hostile towards repairability.
I feel this differentiator is rarely brought up in these right to repair comments and yet should be a critical talking point. Rather, everyone frustrated by a lack of repairability immediately assumes corporate shenanigans. This seems related to Hanlon's razor but for product design.
^[1] Under trays, battery, strut bars, fuel lines, air intake, etc.
^[2] The engine doesn't need to be fully pulled, it just needs to be lifted to where there's room to access the spark plugs.
^[3] People have managed to do this without hoisting the engine, hoisting actually seems easier if you have the tools.
^[4] This is the same reason why SiPs, SoMs, and microcontrollers with an ever expanding repertoire of peripherals exist. It's easier - from a hardware perspective - to integrate a single component that 'does it all' rather than pulling in multiple components and doing the integration yourself.