When Mark Zuckerberg walked into a Los Angeles courtroom on 18 February flanked by an entourage bedecked in Meta Ray-Bans, some people laughed. If this was an attempt at product placement for the company’s newest range of smart glasses, it was jarringly ill-judged: Zuckerberg was about to testify before a jury in a landmark lawsuit that sought to prove that Instagram and YouTube are addictive by design, and he had passed a throng of bereaved parents on his way into the courthouse. But the prosecution team, led by Mark Lanier, were not laughing.This was a serious trial. For the first...