They most likely do. Think about e.g. ranking in their search/recommendation engine. To be able to train ranking ML models, you would need to at least track th

They most likely do. Think about e.g. ranking in their search/recommendation engine. To be able to train ranking ML models, you would need to at least track the views, clicks, purchases, etc. done through their platform. For each search, you want to keep the query string and the results items ids. Let's say, very conservatively, they have 1000 qps on average. We're talking about 100 of millions of events a day.