For example, a one-way ticket costs half the points of a return ticket on British Airways, but Lufthansa charges three-fourths of a full ticket's worth.

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She was carrying a return train ticket and a banner, with some historians now suggesting she instead wanted to attach the banner to the royal racehorse Anmer.

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The reasons such efforts drive up the costs include: A human needs a return ticket, while a robot can go one way.

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