Telcos don't even come close to scale of the companies mentioned. Nor do banks (which have been regulated, they are not allowed to use the information gleaned from transactions, don't expect Facebook pay to honour that), credit cards or loan shark companies (many loan sharks forced out in EU countries)
Kindle Unlimited is not just a subscription service. It's designed to build a monopoly. Kindle Select forbids publishing elsewhere. Apple is being investigated for this practice with Apps in its store.
The USA doesn't have the ability or will to investigate or kerb Amazon. It's appalling that they own Audible, CreateSpace, IMDB, GoodReads and been allowed to buy up other booksellers.
It's time it was stopped.
https://en.wikipedia.org/wiki/List_o...ions_by_Amazon
https://en.wikipedia.org/wiki/List_o...ns_by_Alphabet (Google)
https://en.wikipedia.org/wiki/List_o...ns_by_Facebook
These companies act as if laws of regular companies don't apply simply because they use the Internet. They buy out competition. Sometimes via shell companies.
They make promises to various competition authorities that they break.