Let's be realistic. You are a team of a few persons, using a 'starting' free plan. How great tools and ux could lead you to not have clue on what they are doing

Let's be realistic. You are a team of a few persons, using a 'starting' free plan. How great tools and ux could lead you to not have clue on what they are doing and being able to incur a so high cost by surprise? Also, for example, in which world is it nice to have your service "auto upgraded" from "trial" mode to 72k "full billing" mode without your consent first?