Whoever places an article of clothing in the hamper or the washer has the responsibility to check the pockets. Just because I wore a pair of pants and they ended up on the floor or the chair next to the bed, doesn’t mean that I don’t intend to wear them again so there’s not an immediate need for me to empty my pockets.
Believe it or not, men will usually wear an article of clothing multiple times between washings. When I decide that pair of jeans should go into the hamper, that’s when I empty the pockets. I don’t see any point in emptying my pockets if there’s a chance I’ll wear them again soon because I’d have to put it all back in the pockets. Emptying and refilling my pockets every time I take off and put on my pants just doesn’t make any sense.
If the wife should decide, on the husband’s behalf, that his pants need to be washed (and they likely do) then, since she has taken the initiative, the responsibility for emptying the pockets becomes hers. The rule should be: The person placing an item of clothing into the laundry empties the pockets.