What you are actually getting
A drive-through ceramic sealant is an SiO2-infused polymer that bonds loosely to your clear coat and lasts a few weeks. A professional coating is a much higher concentration, applied to decontaminated paint, and lasts years.
Different products, different prices, both genuinely useful.
Why weekly beats yearly for most people
A sealant reapplied every week never gets a chance to wear thin. Water sheets off, bugs release easier, and the next wash does less work. On Works Club you are getting it every visit for under $40 a month, which is a fundamentally different value proposition than a one-time application.