I think the person probably meant that they had to apply effortful attention while driving. Due to practice, the process is usually automatic/unconscious.
Like if you don't swivel your head and check for cyclists before opening your drivers side doors or do the Dutch reach [1], you're still probably not going to hit a cyclist. Until you do.
[1] https://www.bicyclenetwork.com.au/tips-resources/know-how/du...
Doing these is realiable only if it is matter of habit and you do them automatically, without thinking about it. If you have to focus on it, you will forget about it.
Same with evaluating who goes first on intersection without lights. You should not go through the whole "wait he is from right, but the other is turning ..." you should look at it and know.
There's some good discussion here on the topic. Japan's rail workers point and speak, because it keeps the safety checks in the attentive part of your brain. When things go automatic / unconscious, you tend to miss or gloss over things. This is not what you want while driving.
https://news.ycombinator.com/item?id=18952193
Even pilots are taught to point and say their checks out loud during pre-flight. And flying happens to be one of the safest ways to travel.