The reason is the law, ownership of farms has been regulated so it has been almost impossible to sell it outside the family, bloodline gave you absolute rights, to day it's limited to children and grandchildren, untill in the seventies it was only males that had the right.
This law is in the constitution and has roots back to the viking age so it's over 1000 years old.
It is similar in Austria where the family farm has been family going back 300 years...
The oldest male had right of refusal but with ownership came a lot of responsibilities... all the unmarried women would be wards of the farm until the day they died... the farm also had to support the parents and grandparents and greats if there were any...
My grandmother was an exception as there were no male heirs so as the oldest female the farm was hers and made her a very good catch for a young man wanting to farm and not being the oldest...
I do see tractors of every kind in Europe just few Japanese... it was like this for Japanese cars until the late 80's... they simply were not a market sector but now things are different... having 3 models with preset options influenced many... as the German cars were typically ordered and high end cars required more than money to buy... you had to meet status requirements to buy a 600 Mercedes as an example... the Japanese making A/C standard on the top level really did influence the playing field.
The farms in this region today have very nice tractors... mostly Fendt and Styer dominate.
Going back to the 1950's the single cylinder diesel Styer replaced the oxen or horses... kind of what happened in the US 30 years prior with the Fordson.
One barrier to entry has been high import duties often make products outside the EU less competitive and the cost/availability of parts has remained an issue... where as anything for a VW or Mercedes was easy to get.
As with most things strong Dealer support can make or break local market penetration...
Honda is one example that has been 100% accepted for cars and machinery... like generators.
As to farming the local farms are almost exclusively Diary but this is due to the mountain terrain...
In areas with large open fields the tractors are big... and the farms bigger...