Squalid applies to maintenance and upkeep, not necessarily the presence of drug users and homelessness.
So in the us it’s a budget and planning issue. Places with representation and money get stuff done and other places do not.. largely because nobody cares.
People love to throw this assertion at every American city problem, but really if you are rich in a blue coastal US city, you basically pay Western Europe level income taxes all-in.
A $1M income for a single person in NYC results in an all-in effective tax rate of 46% with a marginal tax rate a bit higher than that.
Plus we have fairly high property taxes so if you were to own say a 3 bedroom apartment commensurate with that income, you'd probably be paying another $30-50k in real estate taxes which is another 3-5% of your income.
I'm NOT saying let's cry for the poor millionaires, but I question that assertion that we just aren't collecting enough revenue.
We have serious rich mans cost disease in US cities where we just cannot spend money efficiently. See everything from homeless services / subway construction / etc.
NYC property taxes are extremely convoluted, but a $2M condo would probably be about $30k/year in property tax, with like $10k variance.
However, a $2M apartment is only going to be like a 2 bedroom, so a Texas $2M home owner might be in the market for more of a $3M-4M apartment in NYC, even accounting for smaller square footage, etc. With the proportional increase in taxes..
$5M+ condos in ATX exist in the Jenga tower with 50+ floors. Even more ridiculous condos are being built in 70 Rainey that leveled a good fraction of what made it Rainey St. cool. The influx of new people has largely displaced and replaced what made ATX cool. There's still some cool bits of ATX, but I'm not telling anyone.
There are homes near Lake Travis that go for up to ~$20M, but the mean average is ~ $1.5m.
But having my tax rate go from 40% to 55% or 60% isn't going to solve, for example, NYC subway construction costs being 8x per mile more than Paris (a more socialist / strong union / pro-labor country).
But, you're right in that just having more taxes won't fix things. There's serious issues in our governments, local state and federal, around actual costs and mismanagement of projects.
It feels weird to hold the opinion that at the same time we need more pro-union and pro-workers rights movements, and at the same time we need to take a lot of unions and what-not to task. ("why do i need to pay $10k for this light to be turned on?")
So in the us it’s a budget and planning issue. Places with representation and money get stuff done and other places do not.. largely because nobody cares.