Are they doing something wrong or choosing the wrong blowers?

Phil, in answer to your questions, yes and yes. A belt or mechanically
driven supercharger (blower) should make boost from near idle. A
underdriven supercharger won't make boost until higher RPMS. A good
example of a well matched supercharger would be the Mercedes SLK
roadster. The old Ford Thunderbird SC V6 was another. The Ford was a
really fun engine, stuck in an outdated chassis.

Hey I represent that :) That chassi was not outdated. Other than
the Corvette, the Thunderbird, along with its brothers the Cougar and Lincoln
MK VIII were the only rear drive American cars with independent rear suspension.
I would also go as far to say it had one of the finest combinations
of ride and handling in the world. Lots of cars would handle better but 
few came close to the ride at the same time. In this regard I would put it up 
against anything of its era. To this day I  am still impressed by
the ride and handling combination when I get out of the RX8 and into
my 94 Cougar. It was a dumb thing for Ford to abandon that chassis.
Some of the rear suspension parts are still used in the Cobra and SUV's. PL

 Turbosuperchargers, i.e. exhaust driven superchargers almost always
start working at a higher RPM since there isn't enough exhaust energy
to spin the turbine until then. The turbo does really improve engine
efficiency though. The recovery of the wasted exhaust energy really
helps. Paul frequently mentions the turbocompound engines that
recover the exhaust energy directly and link it to the crank or output
shaft. The only real advantage of a mechanically driven supercharger
for aircraft use is that the plumbing is simpler. The engine won't be
as efficient as a turbo engine at any speed since you must waste
output to drive the blower. Bill Jepson

The exhaust plumbing is simpler but for the same amount of boost
you need a slightly larger intercooler as the roots blower is
less efficient. I think you are missing something here Bill. There are
two kinds of blowers on the market. Centrifugal belt or gear driven
blowers that don't make much boost from idle and roots or positive 
displacement types that do. The problem is the centrifugal blower 
adheres to the square law. If you gear it to not exceed max RPM there 
is little or no boost at idle. Way back in the old days (30's) Paxton built 
a variable speed belt drive centrifugal blower to overcome this problem. 
Originally used on mining trucks in the Andes. It was sold up until 
recently and may still be available.

Paul Lamar
 
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