Well Well!!!!
Back in the 1970s (maybe even the late 60s?) Tom Karen at Ogle produced a design study that later went on to become the Reliant Scimitar and it had brake lights such as you describe. It had one pair of brake lights near the outer corners of the vehicle (as usual) and then it had several additional pairs forming a continuous band right across the whole width of the car. If you braked gently, the outer pair came on just as with any ordinary car but as you braked harder, additional pairs lit up until the two lines met in the middle of the car by the time you were standing on the brake pedal. Sounded like a great idea to me and it overcame the problem of having one pair of brake lights that got brighter as you braked harder (too dim to see initially and too bright at the end). I was surprised it was never taken up.
From a regulatory point of view, everything's a bit of a mess. The UK has its Road Vehicle Lighting Regs (links in other posts) but now that we're one big happy Euro-family, these are over-ridden by the European requirements. These, in turn, are quite messy. There are requirements for the actual lights themselves and then there are separate requirements for their installation on the car. To make things worse, there are two sets of requirements commonly used in the EC - EC Directives and ECE Regulations. Until fairly recently, one set DEMANDED the use of an additional high-level stop light and the other FORBADE it! (fortunately, the necessary amendents have now been made!) Currently though, they only allow for two (outer) stop lamps to be fitted and one high level light so the Ogle idea would be illegal for Type Approval in Europe.
Once the car has been registered, the Type Approval requirements cease to be relevant and we revert to the old UK Lighting Regs - which allow any number of stop lamps to be fitted - so it would be OK in the UK once that car is registered!
As far as the hazards working when the brakes are applied hard, my 807 (French again!) does this too but I think it might actually be a function of how FAST the pedal is applied as well as how hard. When I first go it, they used to annoy the hell out of me because on the little single track roads round here, I'd often get someone coming round a blind bend way too fast and would stamp on the brake pedal for a fraction of a second and they'd come on. I'd then lift off the pedal as the hazard passed and root round for the hazard switch to turn them off but by the time I'd found it, they'd have gone off by themselves - so I'd actually be turning them back ON again!
Over time, it has started to dawn on me that if I "kick" the brake pedal quickly but not especially hard, they seem to come on. On ther occasions where I'm really standing on the brakes, they sometimes come on as well but I'm starting to think there's some complex logic behind the decision to activate them or not - probably tied up with the "panic-assist" type braking feature it has!
FInally (sorry for the long post!) I think Ernest is OK with his flashing bike lights. I'm not sure but I've a feeling that the UK regs have been amended to make these things acceptable now - I could root it out and check if you want Ernest!