1) Could be one reason that I do not eat peel-and-eat shrimp.
2) Easy to do at home when making Jumbo Shrimp dishes.
. . . break-off head
. . . hold tail and peel shell in one stroke
. . . cut along back with small scissors (eg, fingernail scissors) *
. . . pull out vein, WHILE UNDERWATER
3) Tough to do at a restaurant.
* If the tail has been removed, the vein can be grabbed and pulled
out with the fingers. Messy, but doable with practice. In a large shrimp,
there is a second "vein" which must also be removed.