How does a development boom burden tax payers? Were there no business created in the "unrestricted development?" It stands to reason that a healthy business climate generates tax revenue, instead of increasing the taxes of existing tax payers.
Fundamentally, Mississauga depends heavily on Toronto for the jobs of its population as the manufacturing businesses it attracted are hurting right now and never could sustain the huge population.
I don't want to make it sound like I'm bashing Mississauga. Toronto created this phenomenon of commuter ghettos by ignoring the living needs of middle class families through most of the 1980s and 1990s. Toronto also let just enough businesses escape to these outer suburbs through high taxes, to make it seem like a feasible option to move out there. So people did, but most of the jobs that a professional who lives in these communities works at are still in Toronto itself.
For the most part the only thing keeping downtown Toronto itself from being a mess is that it's the financial hub for Canada. This sphere of influence is not necessarily permanent though and I worry about this city a lot. Alberta is where a lot of the resources are and it would make sense for the financial sector to be there. We like to poke fun of Albertans because they have all their eggs in the oil basket. But right now Toronto has all its eggs in the banking basket. It's a very fragile proposition.
That's fine as long as the people living in those houses are tax-profitable middle class dual income. As soon as they aren't you have just built a 500,000 person slum to fund.
Whether a city is struggling or not right now, or will struggle in the future, is largely a question of how high they let the payroll and pension benefits drift.