This simply isn't true. There are a few who did that, but they're the exception, not the rule.
Shady unicorns: Uber (too many to count), AirBNB (spam), DropBox (lied about encryption/security), The Honest Co (lied about product quality)
Not Shady unicorns: Xiaomi, Palantir, Snapchat, SpaceX, Pinterest, Spotify, DJI, Intarcia, Stripe, Vice, CreditKarma, CloudFlare, BloomEnergy, Fanatics, Slack, Blue Apron, GitHub, Domo, SurveyMonkey, BlaBlaCar, Lyft, MongoDB, Buzzfeed, Cloudera, Automatic, EventBrite, Evernote, Warby Parker, Docker...
The narrative that "everybody cheats" is just something that cheaters tell themselves, so they can pretend that their behavior was warranted.
That said, it's worth discussing these things before applying to a company, because dishonesty creates massive risk in the company, so if you hear and answer that sounds like 'downandout's, you need to devalue that company, because their lack of ethics creates risk for that particular company, and it creates reputational risk for you.