A responder's perspective.
I'm a first responder, and the regional Logistics/COML.
Background:
Any incident, no matter how big or small has three communications needs:
1- Initial notification of responders that their services are needed.
2- Wide-Area command and Control.
3- Localized Task Tactical Communications.
For the first and second, FRS is useless. Don't even go there.
The third is where a supply of (inexpensive, charged, exercised) FRS radios can be priceless.
Scenario: A Joplin-type wide area incident.
The need for initial notification is long past- all available responders already know they need to be doing something and report for assignment.
You can assume that wide area command and control infrastructure is either damaged or saturated into chaos. Surviving assets need to be available for upper-level comms between Command and field team leaders. Tactical short-range communications within a field team on a wide area channel only adds to the saturation. The organized C&C need becomes the biggest nightmare for us comm types. Hopefully there are enough surviving systems that the command structure can communicate with its field leaders. Pre-planning, pre-programming and creativity are key.
Cellular systems are probably off the air or so saturated as to be less than useless, although SMS and Internet may still work.
Task tactical: this is where a task leader has to communicate with his own team members typically over a distance a few blocks at most. Using a wide-area channel to ask Bob if he looked under that rock ties up the entire regional system with traffic best handled on a short range system. There may be a few such teams, or dozens. The tactical team leader still needs to have access to a command and control system to communicate up to his Chiefs, but all his Indians don't. 90% of the tactical comm needs reside in a small localized bubble.
There are many national interoperable channels and local proprietary channels that can be assigned to a specific team's tactical needs, but mutual aid responders from far away won't have the proprietary channels. Getting the national channels pre-programmed in any organized fashion is a daunting and politically painful task, and usually part of someone's plan for next year.
FRS radios are cheap, plentiful, and perfect for talking a couple of blocks. Having a crate of FRS radios ready to hand out to supplement field tactical operations is a good thing. I would much rather hand a volunteer teenager assigned to a non-hazardous door-to-door search team a $20 FRS to talk to his team leader instead of an expensive (and possibly scarce) $500 public safety radio. There are 14 FRS channels available, and since their range IS short, channel 2 can be used for one team on the north side, and again or a different team on the south side without interference. The public-safety quality radios (and their frequencies) can then be assigned to the folks performing real life and safety functions.
Don't criticize any local government for using them; encourage them to go buy out the local discount store on a calm sunny day, and have caches of FRS radios kept ready in more than one survivable location.
Another benefit is that if you are trapped in your basement with a FRS radio, there is a better chance that someone on the street will hear you.