No, it is absolutely not.

Merchants can price their products however they want, and they have no obligation to sell to you. Customers can purchase a product if it suits them, including the price, and they have no obligation to buy from them.

The rational thing to do if buying a ticket from A to B is too expensive is to not buy it, let alone buy a ticket that flies to C.

>Being blacklisted is quite obviously a cost.

Don't break contracts you've signed if you don't want to get penalized.

>Passengers being blacklisted means that _rational_ customers doing this won't tell the airline.

Rational customers will tell the airline that their plans need changing/cancelling. This is just common decency as a human being, my dude.

>If the airline didn't want passengers to skip the final leg of their flight without telling them, they could simply allow the customer to notify them without extra costs. They choose blacklisting (or charging to to "change" your ticket to not take the final flight) and this is the result.

Sure, because airlines (and merchants overall) don't like it when customers try to change the deal on short or no notice. That said, if it's due to outside factors most airlines will try to accomodate you.

If you want to change the deal for unjustifiable personal reasons, of course you will get penalized.

>I mean I get that you work in the airline industry and hence align your arguments to those that profit the airlines,

I'm not, and I'm not sure where you drew that conclusion from. I am familiar with the aviation industry because I have family and friends who work(ed) in it (pilots, ATC, etc.) and I am a very frequent flyer myself.

>you really should accept that the airlines are knowingly creating this environment and that customers are just reacting exactly as you'd expect.

Most customers by and large are reasonable, they buy tickets that take them to their desired destination and the airline honors it. It's not a super power to be a decent human and conduct yourself professionally.