FYI companies should be reimbursing travel expenses for this travel. As a candidate it's worth clarifying to confirm so you don't get some oddball startup trying to force candidates to pay their own travel, but every big company travel interview will be expenses paid down to your travel to/from the airport and the meals you eat along the way.

The time commitment is real, but on-site travel is almost always reserved for the last round on-site. Often as a final pass verification, or when the company is down to a couple of final candidates. Companies aren't flying every applicant out for all of the interviews. If you get to that point, you're close to the job.

Well, maybe some things should be expensive.

If the cost of hiring the wrong person is huge, the cost (in terms of time and money) of conducting on-site interviews is almost certainly lower.

Also, in terms of the costs to the applicants, this touches on the oligopolistic nature of so many industries today, which has resulted in high concentrations of the most desirable jobs in places with the highest costs of living.

Basically, unless you already have a FAANG job or are independently wealthy, it's not easy to up and move to Silicon Valley, Seattle, etc. and job hunt.