The article mentions the lack of drinking fountains due to the plumbers' strike, but not the fact that they only had the capacity to hook up either the bathrooms or the water fountains and Disney picked the bathrooms [1].
It's also pretty remarkable that they finished the entire thing in a single year. For a modern comparison the new Star Wars expansion took 3 years to complete with just one working ride (the second ride will be open in December, so 3.5 years from construction start). I wonder if that's due to more relaxed laws surrounding construction back then or another factor.
[1] https://mentalfloss.com/article/541360/disneyland-disastrous...