Why grocery stores in US have so many discounts/sales?

I watch a lot of grocery store haul videos from America and I tend to see almost everything always on sale. It's not just some random items on the shelf with a deal, but literally everyday products you use daily like meat, fruit, vegetables, milk, energy drinks, toilet paper and so much more!

I've been to almost every European country and they don't even come close in deals and discounts like American grocery stores. Even the big chains and countries (Tesco, LIDL, Edeka, Aldi in Germany, UK and France.)