Florida SunPass toll signage not purple?

[machias]

Why do we need completely purple signs to begin with? Back in the 50s they deemed that white on green was the most legible color at high speeds, now we're going to start dinking around with colors because motorists are too distracted to figure out what lane they're suppose to be in without a big picture?

I can see a regular guide sign with a purple banner on it or something, but making the entire sign purple is more lowest common denominator catering actions.

[vdeane]

In any case, there's no need for purple to be so restricted.  How common are transponder-only roads anyways?  The only ones I can think of are HOT lanes, a few exits on the PTC, and the former Wabash Bridge.  Just make purple for all all-electronic tolling situations and use white "[logo] transponders only" panels similar to the "passenger cars only" messages for NY parkways.

[Pink Jazz]

Why do we need completely purple signs to begin with? Back in the 50s they deemed that white on green was the most legible color at high speeds, now we're going to start dinking around with colors because motorists are too distracted to figure out what lane they're suppose to be in without a big picture?

I can see a regular guide sign with a purple banner on it or something, but making the entire sign purple is more lowest common denominator catering actions.

Plus, the MUTCD doesn't set any minimum retroreflectivity values for purple sheeting, and as far as I know no studies have ever been performed (unlike blue and brown, which the minimum retroreflectivity values will probably be added to the next MUTCD).