I think the idea with the Burbs was they were more likely to have passengers than the 2500/3500 pickups. Families getting killed in new Suburbans would be bad PR for GM.....
When our first '99 Burb got wrecked (the most severe wreck that eventually totalled it) the bags went off. Probably helped my Dad walk away unscathed from the wreck.... They got hit by a red light running and speeding fwd Monte Carlo, while they were at low speed just coming into a left turn they had the green light for. Bent the frame and wiped the front end on the Burb, but that ol 5.7 Vortec was still running even though vital fluids were coming from everywhere.
The MC on the other hand, those two idiots went to the hospital, and the engine ended up on the console. No insurance either which is one reason why we have uninsured motorist coverage.....