I don’t understand how tech companies aren’t being sued for reneging on their promises, it seems like an announcement like “unlimited storage forever” is a unil

I don’t understand how tech companies aren’t being sued for reneging on their promises, it seems like an announcement like “unlimited storage forever” is a unilateral contract that has been broken. If someone puts up a reward sign for a lost dog and a stranger finds and returns your dog, you can’t just say “actually the terms have changed”.