I don't disagree, but sometimes I do manually select the network because

1) esim provider may only support 1-2 out of 5 networks. Why wait for the phone to auto try all of them versus just forcing it to the network that I know should work.

2) some global payg providers have different pricing per provider (nxtlsim, unisim comes to mind).

3) sometimes the supported network rejects the first attempt or so (maybe it hasn't gotten the auth handshakes with the foreign provider yet)

4) there is this concept for network steering, so the phone may not be actually using the best signal, just choosing the signal that has lowest cost. Some IOT sims say no network steering and will choose best signal

5) back in the earlier LTE days, it sometimes was better to drop down to 3G than LTE (LTE was oversubscribed). Not choosing network, but choosing network bands

https://www.telecom26.ch/blog/what-i...ing-of-roaming