Why don’t some SaaS buy buttons go to checkout?

I’m seeing a trend when looking at pricing pages for online saas applications. When you see a tier with the price and features you want you can hit the “purchase” call to action button. But, instead of taking my money they guide me through signing up for the free trial version. Why is this pattern so common? To me, it seems if I’ve committed to pushing that button I’m ready to give you money. Why derail that process?

Examples: Clickup.com Monday.com Asana.com (has a small link below the button to actually purchases it)