I have very vivid memories as a child of walking through Brookwood Cemetary in south east England seeing a big machine crunching up headstones. Vast swathes of the place was flattened. The cheat code here seems to be "topple testing" for health and safety reasons.
It's the UKs largest cemetery and in a shocking state:
There is a park in Brussels where you literally walk on alleys paved with tombstones from the Jewish cemetery. You can still see some of the inscriptions there.
On the continent, afaik most countries work on a lease system, you rent a plot for a few decades (which may or may not be renewable). Some countries have a “perpetual” lease with an ongoing fee, a few years after the payment stops the plot gets cycled.
‘Course space requirements are also a factor, if you have a family plot in a depopulated village in the countryside odds are good plots will be cheap and renewable forever.
Old church with over hundred years old tombstones around it is literally an English landmark. Even in central London. Tombstones you mention belong to people from wrong social class.
I am not even sure about social class. In any case these old cemeteries are preserved probably more as historical artefacts, like an old Roman wall would be in London, rather than out of respect for the dead.