It's pretty common here (UK) for new-builds to be derided as cheap flimsy throw-away things and old houses being built to last the heat death of the universe. It's probably true from a house skeleton perspective but everyone also knows the new builds (usually) have better insulation.
Do new UK homes use reinforced concrete slabs? It is my understanding that those are fairly short lived in UK housing terms anyway, with average life in the 50-75 year range.
Unless damaged by frequent earthquakes or water seeping into the structure and corroding the steel, or freeze-thaw cycles, reinforced concrete does not degrade significantly with age. The range you quote is more typical to things like concrete infrastructure directly exposed to the elements. Modern HPC concrete structures can be guaranteed for 100 years with proper maintenance and will probably have a natural life of multiple centuries.
