not only no choice...

No information - They rarely have any information (you have to go through several menus to find out your plane on most sites). They don't know when / where the plane was last serviced [0].

No framework - Your average consumer of air travel is not equipped to accurately evaluate that information should they even have it. (c.f., 'if it's not Boeing I a'int going [1]). They cannot make rational and informed decisions without information and a rational decision making framework

No control - They have no control over whether that plane is changed for operational reasons even if they have the information and a framework to evaluate it. You may not even know until you are onboard with the door shut unless you are really well informed about airplanes that the plane model has changed (e.g., I avoid A321s because

No recourse - Even if they consciously choose a plane based on information and an informed framework and then it gets changed what can you do? Are you even going to know until you get on the plane at which point what do you do? Do you think you get a refund?

[0] https://www.vanityfair.com/news/2015/11/airplane-maintenance...

[1] https://news.ycombinator.com/item?id=19780372

It's not hard to see which planes fly which routes.

It's also not guaranteed which plane will fly which route. Every airline has "substitution" rules in their conditions of carriage, and frequently use them.

Depends on airline. Southwest, for example, has Boeing-only fleet. JetBlue has only Airbuses and Embraers.

The odds of buying a JetBlue ticket and ending up on a Boeing are fairly low compared to flying Southwest.

Boeing just bought Embraer, but I assume that it will take some time until they the quality of products start to fall

Plus, flights get cancelled, and passengers get re-routed last minute.

I can't recall any plane crashes that also involved a plane switch. So getting bumped to a different plane type and crashing is incalculably rare.

A lot of routes have only one airline though.