I don't know for sure what part of the bbq lighters that altitude affects but I think it's the butane. I've tried a dozen different brands and it's always the same. We camp above 6k regularly and they won't light. I don't think it's the piezo that fails. Our camper stove has one and it works anywhere but it's lighting propane.
Rocky:
I live at 6,400' elevation and regularly camp at elevations between 11,000' and 12,000'. I've never had problems with butane failing to light. It performs poorly below freezing and fails all together below 0°F. If temps are warm, then higher altitude actually improves performance because the low ambient air pressure at high altitude increases the differential pressure between inside the canister and pressure outside the canister.
I think there's some other problem plaguing your BBQ lighters. Are they the kind that have the long pipe? If so, it takes an extra second or so for the pipe to fill with butane. You need to hold down the fuel button for a little while, then pull the trigger to light the flint striker.
The next time that you change the propane tank on your camper, and then use your camper stove, note that it takes a while for the pipes to fill with propane. And the stove won't light during that few seconds. Once the pipes have filled with propane, the stove lights properly every time. BBQ lighters work the same, only the pipe is shorter so the wait time is less.
KC
