Tom,
One can be "grandfathered" into a professional engineer status in many states, but you have to document it pretty well, and yes it does seem like a barrier, but its also like filling out any application... can you deal with the details and get it done?
Um.... No they can't.
Nationwide, folks eliminated the acceptance of an oral exam about 2002, and removed code exemptions for folks that were incumbents in certain responsible charge jobs.
Now, states will grant professional engineering licenses via comity. In fact, the organization that administers the test runs a record maintenance service as a side business. However, establishing that is itself a rigorous process - as it should be.
We have disasters like the I-35W bridge in Minnesota, or the Kansas City Hyatt Skywalk, and folks are clamoring for less restrictions for credentials of folks responsible for such? 100 people died in Kansas City over a stupid mistake from an entry level drafter that wasn't caught by more senior folks.
Look at what happened in Atlanta Sunday. A bridge on a major interstate was irreparibly damaged and will be out of service for an extended period of time causing headaches for millions.
And how many injuries or deaths from this incident?
Zero.
I rest my case.