We've lived this first hand... Especially fourth grade when attendance counts for middle school admissions.
Some middle schools take points away for missing as little as 3 days (most others at five)- which considering that's over an entire school year surrounded by legions of the walking dead, is insane to expect.
The workaround for admissions is that once the kid is counted as present at the beginning of the day, they can go home sick without it being marked against them. So, nobody keeps their kids home... It's like a MASH unit in there at the beginning of the day. Ashamed to say, we did it too (never with a bad fever or throwing up like other kids who walk into school...our kid caught Scarlet ####### fever in K because of this- as opposed to the other parents who inflected typoid Timmy on the world, we kept Jr home for a week).
And considering a lot of these kids are getting all 4s for grades and tests, the difference in the middle schools' admissions rubric can and will come down to those points marked down for absences. Our son missed three days- which basically eliminated him from one of the schools he was interested in.
It's so dismally wrong.
As is the ranking process. The better schools will only interview kids who rank them first. But you can only rank one school first, so that eliminates even consideration of up to half a dozen great schools that lil Skippy might have thrived in.