3G on iPhone 12 Pro Max

Why is Apple so reluctant to reinstate the 3G switch in cellular roaming settings. Phone will stay on LTE with 1 bar. Can’t make a call and no internet access. When it does switch to 3G I get 3-4 bars but as soon as I try to make a call it switches back to LTE and drops the call. I am still able to force to 3G on iPhone 8, 7 and SE but no option for 12.