Where is your evidence for that? It used to be Bing and Yandex, but now it’s just Bing. They use other non search engine APIs and do a small amount of crawling AFAIK. Details of who uses what here: https://seirdy.one/posts/2021/03/10/search-engines-with-own-indexes/
Some discussion on that here: https://lemmy.world/comment/11859761