Several times a week I invoke Siri and say "what is the temperature?" Note, I phrase my query exactly like that, with no variation. About 80% of the time Siri responds quickly and accurately. But ~20% of the time it doesn't respond verbally at all and instead triggers a web browser search for 'temperature'. WTF?
This inconsistency is maddening, and inexplicable as far as I know. This is the kind of thing you'd have expected from Siri in the immediate period after its launch in 2011. It's now almost a dozen years later.
There is variation in product quality at any large institution. More than most, Apple generally strives for excellence and occasionally settles for mediocrity. Not only is Siri nowhere near excellent -- at best, it's a mediocre, largely stagnated service -- it can be downright bad. This is inexplicable, very frustrating when it happens (for me, at least weekly), and utterly disappointing. Steve would not abide.