It would be "enough" if all the major transit ISPs did it and it would be helpful if all the major residential ISPs did it. If non-RPKI routes can't propagate through transit ISPs, that makes it a much less useful thing to do.
They've listed way more than 4 (and those 4 are also massive), click "Show all".
There's 254 operators marked as unsafe.
It's not on the list so imagine there is a fair few missing, would be neat to have a table you could filter by country, provider type (cloud/isp etc) based on real results from users.
edit: there's a show all button to expand the table
But on some level that's like assuming the reason the guy with the handgun is on your plane is that he's a sky marshal and not that some idiot let a concealed handgun through security. I mean, sure, maybe, but, maybe not.
Without asking it's just a guess and I haven't asked. Maybe I should.
Not sure if it makes a difference, but I had a T-Mobile SIM card I bought in Seattle in 2010 and was carrying from phone to phone for years, but I recently replaced the SIM because I heard newer t-mobile SIMs can do better finding 5g coverage.
T-Mobile USA, AS21928 does NOT implement BGP safelyMajor ISPs like British Telecom (core UK telephony), NTT Docomo (Japan), Vodafone Espana (showing that Vodafone isn't doing it globally), Starlink (showing it's not a old tech problem), Rogers (US ISP) are listed unsafe.
I think the 31 is a misleadingly positive picture.