These are networks added by your carrier you can’t remove. They have equal priority to your real networks.
In my case, 2 neighbors have freebie wifi/modem combos blasting out 1-bar hotspots that match my carriers free hotspot SSIDs, so all my family’s personal devices constantly switch between my real home network and these “hot spots” with no way to stop it short of removing everyone’s SIMs
You'd need an extremely strong reality distortion field to advocate for it. I can only guess it's a way for the telcos to offload 5g traffic.
In the Android world, if Samsung/Telstra introduced something similar in Australia that'd be enough for me to jump ship to another manufacturer that didn't. There's an auto-enabled "Hotspot 2.0" feature that I've turned off; it's not ideal that it's on by default but for people on lesser data plans it could be convenient. It's a simple toggle to turn off, nothing's forced.
But I am shocked that they would force connection to open ssids.
In my case I disable auto join on all and they’re all back on in 4-5 minutes.
I was also able to verify this as the device will still really connect to the “disabled” hot spots, even after switching it off. Just took a while for the profile to resync.
Edit: only 5 of 9 re-enable auto join after I disable it.
Looks like comcast xfinity type networks are being imposed too. The xfinity App may be toggling these XFI, Xfinity Mobile, xfinitywifi pieces your way too.
The Xfinity hotspot service typically has two SSIDs going: "xfinitywifi", which is unencrypted and has a captive portal to log in, and the "XFINITY" network, which the installing the profile enables access to and which is encrypted with 802.1X authentication.
For everyone except apparently the carriers, Apple is very strict about the opt in nature of managed WiFi networks.
> even after switching it off
This might be your issue, because after a restart your iPhone no longer has access to your saved Wi-Fi credentials, but it can still use EAP-SIM to join T-Mobile's Wi-Fi network first. But I see your point that it does not respect the "Auto-join" toggle.
If this happens often enough to annoy you, you could file this bug with Apple by typing "applefeedback:///" into Safari. It could take some guesswork to figure out what component to file this against.
Probably not a US thing. Its an IOS thing as that is where you can delete/forget networks you have joined (that arent in range anymore)