“At LinkedIn, we’re committed to respecting what’s yours,” says the narrator of a video titled “Who owns your content? You do.” They continue: “So we’ll always ask your permission before using your content in the ads, publications, or websites of other companies.”

This should go without saying. Our content should not be used in third-party ads without our knowledge or consent. Social media sites should not use content we post for business reasons we didn’t intend.

Yet from a legal perspective, social media sites do have broad rights to use any information you provide. “You own your Content,” promises the Twitter Terms of Service, followed by a long paragraph granting Twitter the rights to use, adapt, share, and distribute your content worldwide. TikTok, likewise, claims “an unconditional irrevocable, non-exclusive, royalty-free, fully transferable, perpetual worldwide license” to your content. Instagram claims not only a broad license to your content, but also permission to show your username, photo, likes, and relationships in connection with third-party ads.

Social media sites like YouTube and TikTok could also, without violating any laws or their own terms of service, charge users to access your video. Or screen your video at their exclusive film festival. Or publish a book containing your status updates. Or set up an art gallery to display your photos. Imagine Twitter University, where users pay to access curated content from (uncompensated) experts. It could offer courses in art history or screenwriting or user interface design simply by collecting existing commentary, links, videos, and photos without user permission or compensation. You might not even know your content was included. And it would all be perfectly legal.

Social media companies can’t afford to alienate creators and business partners, so YouTube probably won’t produce its own film festival with user-generated content anytime soon. And Snapchat probably won’t make and sell music tracks featuring your voice. Even though they could.

The main force holding social media companies in check is market pressure—and markets change. When the risk-benefit calculation changes, and they can make money in new ways without losing too many users or sponsors, social media sites won’t need your permission. They already have it.

The law generally disfavors “contracts of adhesion,” in which the more powerful party sets the terms and the weaker party is stuck with them. But contracts of adhesion are allowed in business-to-consumer transactions because businesses can’t be expected to negotiate with every customer. Customers have two sources of leverage: their market power (they can walk away if they don’t like the deal) and consumer protection laws that prohibit deceptive or unfair business practices.

Social media companies, especially long-established ones with huge user bases like Facebook, are hard to walk away from. Users who have invested years into building networks and troves of content have too much to lose: memorials of life milestones, personal and professional contacts, archives of creative work with reactions from fans. Facebook users have repeatedly threatened to boycott or #DeleteFacebook after the latest controversy, but the site’s user numbers continue to rise year after year.

With limited market power, social media users are left to rely on consumer protections against deceptive or unfair practices. These are intentionally vague terms, designed to adapt to changing markets across industries. By definition, deceptive and unfair trade practices depend on judges’ assessments of reasonableness and relative benefits. Both are subjective and dependent on context.