Manual, or standard, transmission cars are an example of less than ideal usability. They exist because there was a time when manually shifting gears in an automobile was the only choice. However, manual transmissions are still offered today because they are cheaper than an automatic transmission, they can give better gas mileage than an automatic, and for sporty or performance cars, they are just plain fun.
My car has a 5 speed manual transmission, and I enjoy driving it in pretty much all situations except for heavy traffic. In heavy stop and go traffic, I have to constantly shift into and out of 1st gear, and repeatedly use my clutch. I cannot simply just let off the brake and give it a little bit of gas like in an automatic. I would consider this a constraint that leads to unnecessary wear on the transmission parts.
Also, someone who is not familiar with manual transmissions cannot simply hop into my car and drive it with ease. In an ideal, usable world, anyone who has a license should be able to hop into an automobile and drive it. Thus, for those that only know how to drive an automatic transmission, manual transmissions do not fit their mental model.
To fix this issue, automotive manufacturers should begin to phase out manual transmissions and replace them with semi-automatic transmissions. Semi-automatic means that control of shifting gears is still the responsibility of the driver, but there is no clutch, or h-pattern shifter to worry about. Usually, there are paddles on the steering wheel or a sequential shifter on the console. This is the ideal setup for those who want ease of use but want to remain in control of the transmission. Many performance and exotic cars nowadays use this setup (pictured below).