Just read the Wiki article about heat exhaustion and the complications of the 2003 heatwave. Here is a telling paragraph:
Not everyone blamed the government. "The French family structure is more dislocated than elsewhere in Europe, and prevailing social attitudes hold that once older people are closed behind their apartment doors or in nursing homes, they are someone else's problem," said Stéphane Mantion, an official with the French Red Cross. "These thousands of elderly victims didn't die from a heat wave as such, but from the isolation and insufficient assistance they lived with day in and out, and which almost any crisis situation could render fatal."[7]
Not simple thirst then, but not knowing how to keep body temperature normal in tropical heat. Very sad.