The government tried to do it on a logical basis from start of June. For primary schools open up for a few years , small classes of no more than 15 but usually fewer, staggered starts, some flexibility so not every day, make attendance non- compulsory . But the unions generally objected and parents were complaining, some large councils were uncooperative and blocked the reopening and some staff were unfortunately happier being paid to stay at home most days on full pay. Some parents were also unhappy that they couldn't take/pick up children to and from school as grandparents couldn't help.
What you are suggesting is being done for year 10s and 12s where appropriate at secondary schools but even that is proving difficult for some schools