Okay, but how many business flights are actually last-minute like that? Whenever I've flown for work reasons the tickets were bought at least a week in advance, and usually 3+ weeks in advance.
Likewise, there are plenty of non-business flights booked last-minute like that, too - like, as a personal example, needing to book a same-night flight to help a family member drive cross-country with her kids and personal belongings so she could get out of a dangerous personal situation.
All this being to say: if price differentiation between in-advance v. last-minute bookings is actually intended to make business travel cost more than leisure travel, I'm thoroughly skeptical of that intent being fulfilled in practice. Seems more likely that it's simply a matter of things costing more when they're more scarce (as seats on an airplane would become as it gets closer and closer to the departure time), and that just so happens to impact business travelers more than leisure travelers.
I would guess most of your exposure to business travel is within tech or consulting, which rarely require last-minute booking. I would imagine most last-minute bookings for business travel come from people in sales. I’ve seen many sales people find out a prospective client is open to meet and immediately hop on a flight just to potentially make a sale. The opportunity cost is worth it even for small businesses. My exposure to this was for wholesale and retail distribution of consumer electronics but I’d imagine that this would apply to any business with a sales team.
About half of the work trips I've been on, the tickets were booked at most a couple days in advance. The most expensive ticket I've ever bought was an economy United cross country flight to LAX for $1500 (booked about 14 hours in advance) and I've done a lot of vacations to Europe. We booked it last minute because we didn't know when the project would be ready to deliver and once it was, we had to deliver ASAP. I was on the ground in LA for about 12 hours before flying home. Awful trip. Largest ratio of dollars spent to enjoyment received I've ever experienced.
I almost always book tickets for business travel 1-3 day before the trip. I am completely price insensitive (I do not care if my employer pays $100 or $400 for the ticket), my schedule is hard to predict ahead of time (if there are no important meetings on Monday, I will fly on Monday. If something important pops up I may fly on Sunday or on Tuesday). Downside is smaller seat selection (I mitigate by always checking if aisle seat available before booking) and sometimes convenient flights sell out.
My employer does some kind of credit system so we get cash credits for future trips which we can use for nicer hotels next time. Something like that. I don't fly often/ever. I should clarify the credit is the difference of the expected price vs what we paid. So if flight is normally 300 and we pay 200 we get 100 towards future travel. And then there are upper limits to what we can expense and the credits offset that.
I think Google does it now. One problem is see is that people may optimize for price tickets and not business goals to get bigger credit. Business need is 2 day trip but people may extend it by 2 days to get cheaper air tickets but on balance it will be more for the company due to additional hotel cost.
Likewise, there are plenty of non-business flights booked last-minute like that, too - like, as a personal example, needing to book a same-night flight to help a family member drive cross-country with her kids and personal belongings so she could get out of a dangerous personal situation.
All this being to say: if price differentiation between in-advance v. last-minute bookings is actually intended to make business travel cost more than leisure travel, I'm thoroughly skeptical of that intent being fulfilled in practice. Seems more likely that it's simply a matter of things costing more when they're more scarce (as seats on an airplane would become as it gets closer and closer to the departure time), and that just so happens to impact business travelers more than leisure travelers.