You are oversimplifying reliability. Consider this. You have equipment A that when working with B has 90% reliability. Then C that works with D and has 90% reliability. What happens if you build a complex network with A+B+C+D? Maybe you gain a good reliability, maybe you get chaos. What they found out is that you get chaos. So now you have equipment E that has 70% reliability but you can use it for everything. Guess what? You gained reliability from a technology that is more unreliable but it is interoperable.
Which is the point, isn't it?
Can you have that and better quality? Well there are 3 phases according to wikipedia, on beyond phase 2 LTE is considered (which is true) which provides high data rates that you like. So it is not stated that the current phase was the best possible implementation ever.Interoperable emergency communication is integral to initial response, public health, safety of communities, national security and economic stability. Of all the problems experienced during disaster events, one of the most serious problems is communication due to lack of appropriate and efficient means to collect, process and transmit important and timely information. In some cases, radio communication systems are incompatible and inoperable not just within a jurisdiction but within departments or agencies within the same community. Non-operability occurs due to use of outdated equipment, limited availability of radio frequencies, isolated or independent planning, lack of coordination and cooperation between agencies, community priorities competing for resources, funding and ownership and control of communications systems. Recognizing and understanding this need, Project 25 (P25) was initiated collaboratively by public safety agencies and manufacturers to address the issue with emergency communication systems. P25 is collaborative project to ensure that two-way radios are interoperable. The goal of P25 is to enable public safety responders to communicate with each other and, thus, achieve enhanced coordination, timely response, and efficient and effective use of communications equipment.