But on the other hand....our landlord does have a physical copy of the key to our house. I consider this to be a good thing, not a bad thing though! Probably made even better by the fact that legally the landlord has to give tenants 24 hours notice if they want to gain entry(in the UK). They can't just come over whenever without telling me first.
Citizen's Advice confirmed he had no right to be there without our permission.
This should only be acceptable in the case where your landlord is also your property manager. If they're not, then your letting agent should have a copy of a key.
On the 24 hours note, in 8 years of renting in the UK, I can only remember one instance where I was actually told 24 hours in advance. I was usually emailed at 5pm saying "hey, we have someone coming around for X tomorrow at 9:30, we will let them in". I told them no but they still came every time.
Then they were breaking the law, and almost certainly the letting contract. The only question is whether you want to do anything about it or not(legally) - most people don't want to go and fight with their landlord over a repair happening with less than 24 hours notice.
I only had to do this once - our landlord wanted some work carried out in less than 24 hours from telling me and I said ok, but you need to give us at least 24 hours notice, come back the next day - and they did.
The practice in Turkey is to change the lock as soon as you move to your apartment. And most of the time landlords say "I don't want to be accountable if someone enters to the apartment, thus change the locks as soon as possible". And even though the landlord owns the property he is not allowed to enter to the apartment, there is a specific law for that.
Even if you consider these particular benefits, you should be able to make the choice of whether or not to give your landlord (or another trusted person) a spare key.
I do have that choice. I can go and change my locks today if I chose to and the landlord can't legally stop me from doing so. I just chose not to, because to me(personally) the landlord having the key is worth the benefit it provides.