This is a very good question. There are multiple ways to provide constant or near-constant lumen output over a range of input voltages. There are very cheap ways and very sophisticated ways. Poorly designed voltage regulators will likely result in diminished component life (including the LED chips thermselves) at higher voltages in their ranges. While I can't be specific about CAST's approach, I can tell you there are over 100 electronic components in a CAST driver - many of them dedicated to handling voltage variations. Compare that to the lamps you mentioned - take them apart - you can count the components on one hand. In fact, CAST LED driver components are specified to handle up to 40 volts continuous input (over 40 volts - the circuit shuts off). And occaisional spikes of several thousand volts.