Why do airlines charge less for a round-trip trip ticket if the traveler stays over a Saturday night?

为何如果旅客周六停留一晚，航空公司对往返机票的收费就要低？

youdao

If someone like yourself volunteers, they receive a free round trip ticket to be used within one year.

自愿的人可以得到一张一年内有效的免费往返票。

youdao

Man purchasing round trip ticket to board the Statue of Liberty ferry in New York on May 1, 1968. (AP Photo)

1968年5月1日，一个男人购买了前往自由女神像的轮渡的往返船票。

youdao

Look for somebody who's bought a one-way ticket, or look for somebody who's bought a round trip ticket.

NPR: Airport Security Marked by Hassles

When Air Canada implemented its new pricing structure, it also eliminated many travel restrictions that passengers hated, such as requiring a Saturday-night stay and a round-trip ticket to get the lowest fare.

CNN: Pros and cons of a la carte airfare pricing

Delta says it, like other airlines, offers all seats on planes to frequent fliers, just at higher mileage cost than the lowest redemption level, which is 25, 000 miles for a domestic coach round-trip ticket.

WSJ: Frequent-Flier Miles: Best Airlines for Cashing In