My in laws live in Cali. He is middle class. He is paying upto 9% on some of his income.
That is extremely high state taxes...
Saying "he is paying up to 9% on some of his taxes" is meaningless, since he's only paying that on part of his income. All it tells you is that his overall tax rate is somewhere between 0% and 9%.
People's actual tax burden is determined by calculating their total tax payment, and dividing that into their total income. Quoting the highest rate is pure clickbait because every state has different deductions and different tax brackets.
For example, California has a 13.3% top income tax rate, while Idaho has a 5.8% top income tax rate. The person barely looking will say, "California's taxes are way higher!" But that Idaho rate is a flat rate (after deductions), while California has a graduated rate, so the difference is way smaller.
$80,000 income in Idaho (single, standard deduction) - you'll pay $3,000 in taxes (effective tax rate 3.8%)
$80,000 income in California (single, standard deduction) - you'll pay $3,700 in taxes (effective tax rate 4.6%)
So that $80,000 earner in California says, "I'm paying 9% on part of my income, that's crazy high!" But in reality, their effective rate is just 4.6%, barely more than Idaho which is one of the lowest-tax states in the country. You have to look at the bigger picture, not just quote the top rate.