As the GPs on here said, it's about increased demand and inadequate resources to meet that, and no system being ideal for everyone.
I am overseas. My GP is all prebooked appointments. Even with that I can always be seen within a week, often within a couple of days. Appointments are always 10-15 minutes.
Sounds great - and it is - for me, as I have a GP.
The reason they can do that is once they decide their list is full, that's it.They're not forced to take on more patients. The downside of that is I live in a city where lots of people don't have a GP. There is a list of practices supposedly still taking people on, but in reality when they are contacted they often say they are full, or they won't take on complex patients. I work in old age services at the hospital. I have frail elderly patients who travel miles across town after moving house to see their old GP as they can't get a new one in their new location. I see lots of people with chronic conditions who end up going to walk in clinics or ER for routine problems and prescriptions as they don't have a GP, so they don't get continuity of care for their diabetes, heart failure etc. I have patients in a panic as their GP is about to retire and they don't know how they'll get a new one as there is no obligation for another Dr at the practice to take them on. My old GP moved away and his replacement interviewed his patients before deciding to take them over, it wasn't automatic at all.
So I think, be careful what you wish for. It's fine to say look at other countries and other systems, but you have to consider that funding arrangements are different elsewhere. The system is great here if you have a GP, not so good if you don''t. I'm not in the US, it's not about paying or insurance coverage, it's free at the point of (ab)use here too. If you overburden GPs here and make them take more people on, then everyone has a GP, but not such a good service as some of us get now. Nothing will make everyone happy!