Crude oil prices have been falling due to over production. There was a point where there was no where to store crude oil. And then, the coronavirus pandemic killed demand by stopping economic activity. In spite of all these, we hardly see retail petrol pump prices declining. Why?
Simply because crude oil costs is only one part of the cost of bring petrol to the consumer. There is the distribution overheads, petrol station overheads, refinery production overheads, etc. Check out this article that explains the costs involved in the entire value chain of bringing petrol to the consumer.