Too bad the plate cost data wasn't presented. Was wondering which was the most expensive.
In Oregon the cost varies pretty wildly, and some don't have a renewal surcharge.
In Kentucky, part of the registration/renewal fee is an "ad valorum" tax (based on the assessed value of the vehicle). The state constitution requires taxes to be based on assessed value. This value drops every year until it hits the minimum assessable value of $200 for (land) vehicles and $100 for motor boats.