Yea, let's ignore things like massive letting fees and bonds, if the poors want better accomodation they should just rent somewhere better. Absolutely no barriers to overcome there!
We seem to have tenancy system that neither tenants nor landlords are happy with.
Landlords would like to be able to evict bad tenants (damage, rent arrears) more quickly, and have reduced risk of wilful damage. Tenants would like to pay smaller bonds and have greater security of tenancy.
I'm not sure what the solution is.
The cost to a landlord of an extremely dodgy bad tenant can be rent arrears unpaid, serious damage to the house and a pile of rubbish to clean up ... or a P lab.
Perhaps an official register of tenants who don't pay rent or who cause deliberate damage is warranted.
There are already informal networks in place to exchange this information, but they tend to be within a city and fall down when tenants move cities.