Interference Effect
Objects and things that cause a conflict in the thought process and increase cognitive load are known as the “interference effect.” When information is sending mix messages or different signals all at the same time, it is hard for the user to understand and comprehend. This inability to make decisions quickly is one of the many byproducts of interference within a user experience.
Example 1: The Pocket Universal Principles of Design
This depiction in the book of highway and traffic signs illustrates very clearly the Interference effects. 
Example 2: Online Example of Interference Effects from The International Design Foundation
Example 3 : Parking signs near me in downtown San Jose, California
I think your use of the SJ (or any Californian, really) signs as examples of how too many signs can cause confusion or conflict. To add to this, I read about an extreme take on this by getting rid of all road signs altogether. Here’s an article on 99PI — https://99percentinvisible.org/article/shared-space-design-road-signs-suck-got-rid . There are towns in Europe that are testing the complete elimination of signs and doing a free-for-all approach which actually showed a dramatic decrease in accidents/deaths of pedestrians, drivers, and bikers alike. Although people are forced to drive slower, which explains the decreased number of accidents, it also eliminates waiting time for turns. Everyone is slower but more aware. The downside is adapting this system to hold up to accessibility standards of having road signs. Though the accident rate is significantly lower, the accidents that do occur are more often with those who are impaired and rely on certain signals and pavements to navigate a city. Anyway, this is one case study of improving efficiency by reducing interferences.
This principle is something I deal with very often. The logical way in which Engineering teams work, think, and develop tends to make User Interfaces very crowded and convoluted. The attached link shows an extreme case, that probably never happened in real life. but it is a constant testament to the flowed linear thinking that makes things unnecessarily complex and useless. Just like the signs you show in your post. this type of complexities face us designers with a constant push and pool about what should be showing in a User Interface, at a given time, for the given user persona. less is more but more could be the right solution if the user’s mental mapping and process is satisfied. There is an inherited and necessary complexity in any given design, that must be thought and solved from the user’s perspective. A low cognitive-load solutions is always effective and promotes usability. the signs as well as the Microsoft UI from 1997 are both full of well organized necessary tools and information. it is the lack of hierarchy and correct data chunking that make these examples unbearable for the mind to process in a timely manner.
https://drive.google.com/file/d/1my4v4s4eJzJOAxDjgK3yZZOeUD962gGj/view?usp=sharing
Nice post! Just wanted to add an additional example, I found this through a quick google search and thought it fit the description.
https://www.google.com/imgres?imgurl=https%3A%2F%2Fcs3240team18.files.wordpress.com%2F2012%2F08%2Ffurnace-switch.jpeg&imgrefurl=https%3A%2F%2Fcs3240team18.wordpress.com%2F2012%2F08%2F22%2Fgood-interface-design-and-bad-interface-design-an-example-each%2F&docid=UIJ7m2nAfI0_VM&tbnid=eWopxT7X48aMvM%3A&vet=10ahUKEwiNo9-6ho7eAhUzGDQIHQZLBYQQMwhCKAUwBQ..i&w=195&h=256&bih=721&biw=1280&q=confusing%20design%20examples&ved=0ahUKEwiNo9-6ho7eAhUzGDQIHQZLBYQQMwhCKAUwBQ&iact=mrc&uact=8
I can’t find how to edit the comment, but the link works if you copy and paste the whole thing into the browser, sorry about that!
This reminds me of the principle I wrote about, horror vacui. It’s similar in that they both deal with complex and busy designs, though the takeaway is different; horror vacui is mostly about value positioning. It would have been nice to see different kinds of examples. Here’s one I found of a busy street somewhere in Japan with lots of neon signs:
https://cdn-images-1.medium.com/max/2000/1*q7XLgWyfqEvwmgd-rEXVjg.jpeg\
Source: https://unsplash.com/@trapnation