re:  I know, I know...the part I wasn't thinking about is the fact
that the low beams stay on all the time, even when the high beams are
on ...

This is not true.  Check with a tester at the wires, as you'll go
blind trying to see if both filaments are simultaneously lit.  I think
both filaments may light simultaneously but only when in "flash"
position on the switch, that is as you hold it back toward you.  In
normal high beam postition (when you let go), only one filament is
lit.  These bulbs wouldn't last very long with two filaments lit at
once.   As further evidence, note the specifications, normally
55w/65w.  That's for each filament.  If they worked the way you
suggest, it would be additive (like household 3-way lights) and when
the low filament burns out your highs would be just 15w, and that's
not how it works.  Nor are you getting 120w per side on high.  Yellow
(which feels like a dimmer white) is the low beam wire and white
(white hot) is the high beam wire--these are the standard colors used
on all German vehicles and others that adhere to Bosch standards.