They would just find another way to know who participates. A roll call or
attendance sheet being kept at each service meeting, for example, would
fulfill that very nicely. Or turning in a monthly participation sheet to the
bookstudy overlord without listing times, just dates. After all, field service
is mandatory for a "Christian" who wants to be in good standing, isn't it?
Then they'd have everyone meet up later for an after-service head count to
try to ensure everyone did go out in service. To quelch any idea of showing
up for the meetings without actually going out in service just to get their names
on the paper, they'd be sure to have monthly guilt trip parts talking about just that.
If there was absolutely no accounting of it at all, then field service would drop by 75%,
I would think. Just the eager beavers wanting to get ahead in the organization
would actually go...and those wanting to look down on others...and a couple
honest-but-stupid ones.