Very true--which is why residency is taken into consideration when buying a car, etc. However, an example I just ran into last night:
An acquaintance of mine moved from NH to Maine a few years back. Several months prior to that, he had purchased a new car. However, because the car was less than a year old, as soon as he tried to register it in Maine he got nailed with 5 percent sales tax and 5 percent excise tax on a 20K vehicle. This is AFTER the vehicle had already been legally registered in another state.
Don't even get me started on how some states do income taxes. Maine, again as an example, is one of the worst. While they don't nail you for BOTH incomes if you're married (like they used to) it can often be worth more to NOT work.
Example: Let's say I work a job making 90K a year in NH, and the wife has a part-time gig in Maine making 10K a year, for a combined income of 100K, of which her share is 10 percent. Now normally, one would say that she gets taxed on 10K, which we all agree would be a very small amount. Right?
WRONG.
The way Maine figures "their" share of state taxes is that they figure what the tax would have been on 100K of income and take 10 percent (her percentage of total income in this case) of that figure--and Maine has an 8.7 percent state tax that kicks in at 20K/year with virtually NO deductions. So 8.7 percent of 80K = $6960--on a job where someone earned 10K. IOW, when you consider transportation costs, etc., it would be cheaper to just stay at home. Granted, one could work around this by filing married/separate on federal return, so either you're going to get screwed by the feds or by the state--either way, you're screwed.
Final case--the cops in Maine are going around finding people parking cars at their homes which are registered in other states who are trying to avoid paying Maine registration fees. Okay, I get that. However, one guy was given a company vehicle to drive directly to work sites from his house for a few weeks. The company is located in NH, the jobs are in ME, NH, and Mass. What did the cop tell him? The vehicle isn't registered in Maine, therefore he can't park it at his home despite it being a company vehicle without first registering it in Maine.
I wish I was kidding.