Hold on.... surely this is about what you would expect just from kids picking it up from their family/community contacts anyway.
Eg Scotland has 100 cases (ish) a day the past week. Assuming they are equally spread across ages, so no extra spread from schools, then about 15 a day should be school age kids.
Multiply by the 2 weeks quarantine period and you get 210 students with coronavirus without any special spread in school environment. So if anything 73 schools sounds on the low side to me.
Now this is only rough assumptions but it agrees with what Scotland saw in the last few weeks. The proportion of of coronavirus cases that are children didn’t go up once schools reopened. Children are being infected via their community contacts, family etc, NOT via school transmission. So far at least.
@letsghostdance there are parts of Scotland that are worse than others. Our part is fine. Glasgow is bad but it’s down to community transmission. Other areas have schools open without additional problems(yet).