Well, it’s easy to blame “greedy developers” because we all want someone to blame when we are upset about something. But ultimately, Brits have small houses because this is a densely populated country and Brits will not make the trade-offs that might allow floor space per person to be increased.
Do you want more land to be released for development? If so, where? Green fields? We are facing an environmental crisis. We could shift towards really good public transport, walking and biking, reduce car ownership and make use of the space currently used for housing cars (which is a lot)—that is part of the reason why Dutch people have more floor space per person in spite of being more densely populated. But suggesting to Brits that they give up one of their cars and do more PT, walking and biking, tend to go down like a cupful of cold sick in this country.
We could stick with the same amount of total development land while increasing each plot size, by building fewer houses. But this will just lead to a whole lot of different complaints. Because we have a 4 million home shortfall in this country. At the moment, Jane and Anne each get a tiny house. Is it OK that we decide to give Jane a bigger house and garden while Anne gets nothing, stays in a flatshare and can’t have the family she wants?
Or, floor space per person could be increased by shifting towards flats, where you build upwards - again, this is another reason why the Dutch have more floorspace per person on average. But British people are negative towards apartment living (even nice apartments with balconies and shared green space and close to parks!!) and are really really rigid on “children must have a garden!!” In my experience. Leasehold reform might help. But even if you reform leasehold, I just find British people don’t like the IDEA of flats, esp for families. It’s a real cultural thing here.
I don’t think there are any other suggestions.
And so you end up with little weeny lego brick houses and gardens too small and overlooked for kids to actually do much in, all wedged in at weird angles.