In Colorado, an ambitious new highway policy is not building them

I would quibble here, it depends. Another example I am thinking of is toilet paper during the pandemic when it was in short supply. At that time, when we were counting squares of toilet paper and predicting when you were going to run out, people used their toilet paper very efficiently. When it is plentiful, suddenly you don't care about using every last bit as efficiently as possible.

In my previous example in the parent post, everyone is still making it to the grocery store and/or work, but it's a question of how efficient people are incentivized to be when making those trips.

When it comes to highways, I'm guessing that it's more the case that inefficient/unnecessary trips become more economical than typically enabling people to make a given trip at all. I know a lot of people are pretty lazy about planning their trips, I'm guessing there are a lot more of those people than those that cannot go to a city because it requires 45 minutes instead of 30. Just my guess there though, and certainly that is context dependent.

I like your points regarding efficiency of cost for expansion as well. Though, my point is more that induced demand is the minimum efficiency of a resource someone is willing to incur for it to be worth the cost of using that resource. That latter part, is a bit independent of the cost of building that resource in the first place, though that construction cost is still an important thing to consider.

Food spoilage does come into play and creates a lower limit on the frequency. At some point you'll buy so much you can neither store it nor consume it before it spoils. At some other point on the other side of the spectrum - the cost to travel is not worth the convenience of buying exactly what you want each day. All in all, people would indeed prefer to go more frequently for less, but there are reasons to not do so.

Thus, high frequency does give flexibility, and that is really important. It's a big reason why people like to have their own car, and do things like buy one weeks of groceries and not a full months at a time. That same flexibility is why people rationally choose to make multiple trips when they could make fewer. I do find it quite interesting to think about the various 'sweet spots' in these equations, and the various constraining factors.

Per-lane efficiency drops with additional lanes. It doesn't stay the same, and definitely does not increase.

> that being said, does having 50 more buses actually reduce anything, 100 more?

Yes. A typical city transit bus can hold 40 seated people, and a "crush" capacity of about 70. Coach numbers are relatively similar give or take. Typical rush-hour max capacity is probably around 60 which is fairly comfortable.

40-60 people taking up about the space of three cars, instead of (if we're being very gracious) 20 cars, to as many as seventy cars.

If we graciously figure that when stopped in traffic each car is 15 feet (length of a compact SUV) and there is one foot of spacing between them (also gracious), that means anywhere from 320ft to over one thousand feet of lane usage, compressed into about forty feet.

Now think about how much roadway space is used when those vehicles are traveling; those cars have to accordion out to have, say, about one car length between each of them (likely more, but we're being gracious.) Now you're looking at 600 to two thousand feet of lane.

This is why bus-only lanes (either during rush hour or all day) and traffic signal prioritization for busses is gaining popularity in municipalities. One full bus erases two thousand feet worth of cars on that road.

We should be looking at the status quo as "look at how much road capacity is being wasted by single occupant vehicles."