The problem isn’t that the 30% rule isn’t a good idea anymore. The problem is that for so much of the population it isn’t realistic anymore.
Also I wouldn’t be surprised if a terms like housing stress based on the 30% rule is part of official terminology. So it can be used for discussing rental rates, morgage prices and legislation.
Looking at averages like you propose isn’t useful if something bad impacts a whole population.
If teachers are not meaningfully different from the rest of similarly situated citizens, then raising teacher pay alone isn’t the answer. (Maybe building more housing is.)
Also I wouldn’t be surprised if a terms like housing stress based on the 30% rule is part of official terminology. So it can be used for discussing rental rates, morgage prices and legislation.
Looking at averages like you propose isn’t useful if something bad impacts a whole population.