Difference between checkout and sales point

Test No. [color=blue]incompl/advan-16 “At the Shops”, question 3

The trouble with these huge superstores is that they don’t have enough to deal with customers at busy times.

(a) barriers
(b) sales points
© exits
(d) checkouts

Test No. [color=blue]incompl/advan-16 “At the Shops”, answer 3

The trouble with these huge superstores is that they don’t have enough checkouts to deal with customers at busy times.

Correct answer: (d) checkouts

Your answer was: [color=red]incorrect
The trouble with these huge superstores is that they don’t have enough sales points to deal with customers at busy times.
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why not “sales points”? I couldn’t understand and find the meaning of “checkout” here

A checkout is the place within a store, shop or another commercial establishment where customers pay for the goods they have purchased. A sales point is a place where something is sold.[YSaerTTEW443543]

TOEFL listening discussions: A conversation between a student and a registration clerk during registration week[YSaerTTEW443543]