They also require that the strength bars display the highest reception of any type of service it can receive, regardless if that is what it is using right now.
So it may display 4 bars and LTE but it's really 4 bars for GSM service, despite using LTE atm.
They do this because it works when it comes to reviews and perception.
There was a phone that people complained about reception on that was displaying the current service signal strength using a realistic algorithm.
Review sites, etc, complained about it compared to other phones despite it being better in actuality.
A "fix" was issued. That fix was to use the same signal bar algorithm as everyone else. The same review sites/etc were awash with how much better everyone's reception was and gladness the bug had been fixed.