Almost all modern phones allow WiFi to be enabled while the phone remains in flight mode (keeping the cellular modem disabled), and this is allowed by FAA/FCC and, I think, every airline's rules in the US as well.

The reason that phones are banned on planes is no longer due to concerns about interference with the aircraft (which have been, by and large, debunked), but rather because the terrestrial cell network is really not suited to supporting phones at altitude.

Some airlines (e.g. Lufthansa) also install GSM microcells in their planes.

They allow you to completely disable flight mode, once you're at cruising altitude -- and therefore out of range of the terrestrial cell network.

(Whether your cell provider will actually allow your phone to associate with the in-flight microcell is a different issue...)

For flights I took in western countries (US, Canada, Australia, EU), it seems that it is no longer required. China is a major holdout afaik.

US and Canadian carriers definitely still tell you to put your phone in airplane mode.

They do, but they also frequently offer in-plane WiFi so it's clear they're expecting you to know to turn your WiFi chip back on even though the phone is in Airplane mode.

IIRC the "put your phone in airplane mode" rule is a FAA mandate. Airlines can't change it.

I also wonder what percentage of phones actually get put in airplane mode. I don't think I'd bet that it's as many as 50%.

IIRC last time I saw a study on this it was pretty high. Well in the 95% range. But there would usually be a phone or two on every 737 or larger sized plane not in airplane mode.

That would somewhat shock me to be honest. I make a genuine effort to turn on airplane mode if only because not doing so drains the battery and I bet I miss at least one in 20 times. I would hope such a study was based on measuring ehat pople did as opposed to what they said they did.