In a hard water area, the lead pipes get coated on the inside, and this prevents any lead getting into the water.
And in a soft water area, most measurements show the lead to be at acceptable levels.
I replaced a lot of lead piping in my parents house in Aberdeen - to modernise the system. Aberdeen is a very soft water area - the local stone being granite. Cutting open the pipes revealed the original extrusion or whatever markings. If the water had dissolved the lead, then it can't have been by much, even over 50 years or so.