One Sided Terms?

I an any business deal or negotiation, both parties negotiate and come to mutually agreeable terms. In case of software or digital purchases, it seems the providers can unilaterally impose terms, change them as they deem fit even when the user does not want to be bothered by the updated terms. It is even more pressing when it comes to AI models, the companies can scrape and use all the content available for them but explicitly write in their terms of agreements users can’t use the output train their systems. How did we come to this?