When you've guaranteed 4 or 5 nines worth of uptime to the customer, every acknowledged outage results in refunds (and potentially being sued over breach of contract)
Meh, I’ve never seen an uptime (SLA) guarantee that was worth anything anyway. They’re consistently toothless, publicly-offered ones anyway (can’t comment on privately-negotiated ones). I’ve written about it a few times, with a couple of specific examples: https://hn.algolia.com/?type=comment&query=sla+chrismorgan.
But not acknowledging actual outages, yeah, that would open you up to accusations of fraud, which is probably in theory much more serious.