My personal take is that this wording is the reason you see so few public status pages in general, especially ones with automatic and minute-by-minute status history. Better to put it on the customer to have accurate monitoring in place, which most people simply won't have.
A process that involved arguing about what a status page said and when doesn't make a lot of sense if they have logs of what happened.
2) The SLA isn't tied to the status page at all, a customer can request an SLA refund for any reason provided they have proof of damages.
TL;DR: status pages are a helpful tool to let folks know something's wrong and that the team isn't asleep at the wheel, not a legally binding contract.
>why is it legal in the tech industry?
Tech has a history of abusing legal gray areas or else simply ignoring laws it finds inconvenient, enabled by toothless and sluggish enforcement, and using profits from lawbreaking to fund lobbying campaigns to retro-actively make things legal. For recent examples see Uber, Airbnb, Clearview, et al.