Either 1) A local government increases taxes to build a park
2) The federal government increases taxes to build a park
And Either A) A SALT deduction exists
B) A SALT deduction doesn't exist
And independent of this, the federal government collects tax on income to do whatever it currently does.
1A) people end up paying: (income - income.(park tax)).tax - income.(park tax) -for-> park + std_services
2A) people end up paying: (income).(tax + park tax) -for-> park + std_services
1B) people end up paying: (income).tax - income.park_tax -for-> park + std_services
2B) people end up paying: (income).(tax + park tax) -for-> park + std_services
Note 1A, 2A and 2B are all equivalent. In 1B people pay more overall tax to get the same services.
So under B, any reasonable person given the choice between 'should the local government build the park (1B), or should the federal government build the park (2B)', should logically choose 'federal (2B)'.
IE the local government's ability to do build parks is weakened by the lack of a SALT exemption.