Bulgarian speeding fine

So, in Bulgaria when you get a speeding fine, they don't tell you about it. They don't send you a letter. Instead at some, point later on, eg when renewing your passport, you get an official notification that you have a fine to pay, in our case from December 2020. When you then eventually go and pay it you're told the fine will be reduced by 30% if you pay. So our fine was either 70lv if we paid or 100lv if we didn't. Nobody could tell me what happens if you don't pay! All of this for going 72 in a 50 zone. And we weren't even in the country, at the time, but the car's in our name...