How does this work or doesn't it ?

[habibihabibi]

I am abroad and if one household member is exposed to a positive case all members of the household must isolate and test asap. Why isn't this the rule in England ? Surely siblings can potentially carry the virus to schools and parents to their workplaces ?

Testing ASAP doesn't really work though as it can take 14 days for the virus to incubate. So contact on a Monday, test maybe 3 days later when you find out that you have been a contact - the virus may still be incubating so won't be picked up (and your family likely won't have it at that point).

As above you can’t get an accurate test result if you test without symptoms. Testing negative in that instance doesn’t put you on the clear.

Isolating contacts of contacts would mean nobody would ever be out of isolation.

Surely siblings can potentially carry the virus to schools and parents to their workplaces ?

They can't if they are isolating ...

They can't if they are isolating
But from what I have read is if a child in a English school bubble has postive cases all of the bubble isolate but siblings of the possibly infected still go to school.
Here if one family member is exposed everyone isolates and then tests at the end of the isolation period.