I agree, that human error is a key cause of damage. It is what insurance basically covers in the case of people having car accidents, household incidents etc.
Of course the landlord isn't thrilled by this - by the fact the tenant made the error or the cost or the inconvenience. But at the same time, it really is par for the course and something that all Landlords should expect in some form and be prepared for financially and able to deal with professionally when it does happen. Being furious or finding you do t have the financial means to cover it and to offer re-housing just isn't professional.
Yes, tenants are obliged to take resonable care. The Op says this tenant has been there 14 years. Even with reasonable care, mistakes happen. When you make a mistake in your own home, the financial burden is on you. When you make a mistake in a rented home, one of the things your rent money covers is mitigation of that damage - the landlord pays.
Of course, if a tenant proved to be consistently causing damage or accidents, a LL could not renew their tenancy. At the moment with Covid it is impossible to evict people who don't want to go, even if they are in massive rent arrears, but in normal times, it isn't us usual for LLs to not renew tenancies if a major damage has occurred. That though doesn't mean the tenant pays for the damage and actually getting new tenants always costs the Landlord anyway.
Most Landlords who've been in the business for a while or who have several properties will have an idea of how frequently and how expensively incidents like this will occur...and budget for them. But everyone also knows you can be lucky and have fewer than the norm or unlucky and have lots more. There are lots of risks of being a landlord like void periods or tenants who do t pay the rent or cause damage. Again, if you can't face those issues or fund them, it's not the business to be in. It's all part of the complete package of good and bad bits!