Oh Mucky, you didn't read the post. This woman has one tenant and one rental, and lives nearby: having a property manager is not a money saver to her.  Had she attended a property owners class or the like from a plethora of free/low-cost organizations that give such consulting classes, she would have known she had the ability for monthly (not yearly- that's ridiculously long) inspections, and could have avoided this.
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The landlord SHOULD charge whatever the market should bear-- there's no use in having "a good tenant" if the cost to you is exceeding what that good tenant pays you in rent.  And it's only "expensive finding a new tenant" if the market conditions are such that people aren't renting in that area, or at all -- so again, yes: If I am the home owner, I'm considering what the market would bear in making that call.
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Further on the economics lessons, if I go to McDonald's, and then I go to Crow's Nest, I don't seem to find the same kind of people.  Hmmm- must be coincidence.