- Confirmation bias. You remember the irrelevant ads, because they made you do a double take, they stood out as unusual.

- The terrible ads are actually effective at getting clicks from people with similar interests, but less of an aversion to ads, less ad-blindness due to depression, more willing to buy online, ...

- Especially with retargeting (what you describe with the fridge), the CTR is higher than with non-retargeted ads. But it is also one of the most visible forms of advertisement (everyone has a story similar to you, where they get followed by ads after looking at cars or fridges).

The online ad industry fuels the likes of Google and Facebook. Tremendous engineering and research effort goes into making these systems more efficient. Personalization and tracking of preferences is at the state of the art for these companies. Though not the potential best, it is close to the best possible we can do with ML right now.