Incorrect.  Quote from Sound Transit:
 "The vehicle value is determined by using a formula based on the vehicle manufacturer’s suggested retail price (MSRP), or purchase price for commercial trucks and commercial trailer, and a depreciation schedule set by state law based on the age of the vehicle (years of service)."
It is not based upon market value.  It is based upon the the original msrp and a depreciation schedule set by the state that has nothing to do with market value.
As far as "faith and trust", I can only say "Fool me once, shame on you.  Fool me twice, ..."  
There are a bazillion reasons I did not vote for ST3, but the excise tax depreciation schedule is not a valid argument.