We've just escaped tier 3 (England), for now. The south of the county (Nottingham, Rushcliffe, Broxtowe & Gedling) has been moved into tier 3, leaving us behind in tier 2. Most of my family are already in tier 3, over the border in South Yorkshire.
The case rate here has gone up from around 80 per 100,000 a few weeks ago, to 280+ on the latest figures, and is still increasing with tier 2 restrictions. As the data is a few days old when published, I think there's a fair chance that it's now heading over 350, which seems to be the trigger for tier 3, at least locally.
I can't see how tier 3 will work. It seems to slow things down, but it's certainly not reducing the overall numbers - the only advantage seems to be the additional financial support. It doesn't look like a long term solution to me - I can see a tier 4 coming soon.
As for compliance, I've watched neighbours on both sides of me break the rules on visitors since tier 2 was introduced, and one of them is an ex-police officer. One of the cheeky buggers parked their car outside my house yesterday, looked like they were visiting me!