One of the things I noticed about the Bedouin in Sahara is that they tended avoid even the slightest physical exertion in the midday heat. They would get up very early, make the most of the morning and retire to their tents or mudbrick houses well before noon. They would rest until well in the afternoon, by which time they would refresh themselves with a cup of tea and resume their daily chores until late into the night.

It is a very particular way of life from a Westerner's point of view. To a casual observer the Bedouin may seem very easy going, downright lazy. But in reality they are just highly rational people adapted from birth to the harsh desert climate.

I also remember being greatly impressed by the way they rationed water. I don't think their daily water consumption is much above an average Westerner living in the temperate zone. Water is in short supply in Sahara so the Bedouin do everything possible to conserve it. Above all, they restrict any physical activity during the hot hours of the day to keep their body temperature low and avoid sweating. Doing so helps them get by with not much more than the regular 3 or 4 quarts of water per day.

This is also why historically the Bedouin would primarily travel long distance at night. But as far as mobility, they are completely dependent on the camel and now the ubiquitous 4WD. There is no way humans can cover long distances on foot in a hot desert environment. The British learned it the hard way early in WWII (Long-Range Desert Group). It's simply impossible to carry enough water for a long trek on one's person.

The unfortunate French tourists seem to have made every possible mistake they could. It ended tragically, but I am nevertheless amazed that they kept pushing on even once they realized their water wouldn't last long. In that sort of environment they should have backed up to the car very quickly, about the first time they felt the need to take a sip of water.