I wouldn't worry.
A lift with a capacity of 320 kg (4 persons) will not fall if one of the persons weighs 100 kg*.
Serious companies always apply a (large) safety margin: an 80 kg person jumping on gravel is much more demanding than a 140 kg person going to work on a road, also for warranty reasons.
* In fact, a lift usually has a 400% safety margin. So even if EVERY person on board weighs 320 kg, it shouldn't fail, although I wouldn't dare try it...