When you buy a vehicle in Texas. The dealer will issue metal plates in your name at time of sale.
When they have the title in hand and filled out with all the forms signed as well, they will scan those docs to their local tax office and pay the sales taxes & fees. Once the tax office reviews the scans and approves the paperwork they ACH the dealers bank account for the sales tax and fees. After that happens, a few days later the dealer has the privilege of driving to the tax office and picking up your sticker and then mailing it to you.
This is one way it's done, there may be other ways but the above is how I do it.