^^ presumably the people defaulting derive a large proportion of their income from the State, so presumably that income is within reach.
AFAIK council rents are set at a rate that is deemed affordable by the tenant, so it's "won't pay" rather than "can't pay". It's bizarre that the risk of being chucked into emergency accommodation is no disincentive.
You would think so, but this issue came up during the water charges debate.
Social welfare rates are very carefully calibrated so that family types are above various poverty thresholds.
Basically if you have mandatory deductions of rent arrears you tip low-income families into the 'poverty' space.
This is a big no-no for the Department of Social Protection, the co-operation of whom you need for any kind of mandatory deductions system.