来看看,why这小文章用一般现在时?

来看看,why这小文章用一般现在时?
两空格One afternoon,a man rides up to the US-Mexico border on his bike,carrying a large bag.The guard stops him and asks,"What is in the bag?"
两空格"Sand,"replies the man.
两空格"We'll see about that,"says the guard.He opens the bag,and finds nothing but sand.The guard lets the man cross the border.
两空格The next day,the same thing happens.The guard asks the man,"What have you got in the bag?"
两空格"Sand,"replies the man.
两空格The guard checks the bag and finds that again the man is telling truth.
两空格This kind of thing repeats daily for 3 years.Finally the man doesn't come and a week later,the guard meets with the man in a bar."Hey,"says the guard,"I know you were smuggling something.Just between you and me,what was it?"
两空格The man drinks his beer and says,"Bicycles."