What do I even begin googling to find this in my city? Toronto.
For example, I am sure it is not possible in Germany because tenancy contracts that include short-notice eviction clauses are void.
Dutch rent law is stricter than German and it's still allowed. It's a combination of a regulatory framework at a higher level, and anti-squatting not being 'renting' but 'borrowing'. (terminology is a problem here since there is no word in English for the civil law legal form that is used. The closest is 'lease' but that is used for regular renting already in English.)
More to your point, it certainly exists in Germany, and is generally called "Hauswachter" (that is, the people living there, not sure about the form itself). Companies offering it are for example http://de.cameloteurope.com/ .
I have friends who did this in a nice house in an expensive town for a couple years, taking advantage of the low rent to save for a down payment on their own home.
All this to make sure we would flee the place and never come back, thus keeping her cushy low-rent 'temporary' housing. Any wonder this is not a popular option with landlords?
When I was a landlord, I let my tenants stay in the house while it was for sale (at the end of the regular lease, they signed a month-to-month lease to cover this), with the understanding that they were to keep it ready for showing with 12 hours notice. The one time this was a problem I made it very clear that they'd be out at the end of the month if it every happened again. It didn't!
http://www.standard.co.uk/news/i-moved-out-for-decorators-an...
Worth noting that squatting was pretty much never legal in Scotland - although we do have the Right to Roam over land which I don't think the rest of the UK has.
http://en.wikipedia.org/wiki/Freedom_to_roam#Right_to_roam_i...
A properly secured property, where you make sure all windows are repaired and doors and windows are locked, is basically safe from squatters, assuming you get all the entrances (many old Victorian houses have common loft spaces, so when residential squatting was legal people could find one unlocked door in the street and claim a whole terrace. I heard of a priest who did it once in Lancashire somewhere and then used the row as almshouses.)
A common tactic is to do it in two passes. First one dude comes along, smashes in the locks and walks away. Then a couple of night later a second group of dudes come along and find the house unlocked and 'legally' move in. So you basically have to have security people check your buildings at least once a night.