Of course people shouldn't phone an ambulance if they don't need one, and I luckily haven't had to, but a lot of posters saying that you don't get seen any quicker seem to be missing the point that paramedics are healthcare professionals, so even if you still have to wait a long time once in a&e, you will already have been seen by a healthcare professional, and in many cases they will have been able to provide some treatment, or at least assess the urgency (which most of us aren't actually trained to do for ourselves, so understandably sometimes we panic). Ok at the moment it still might be quicker driving there if the ambulance is going to be hours and hours, but you don't know how long it's going to be until you phone (do they even tell you then?). Also I'm unlikely to be sure, in case of a fall or bad injury, if it is safe to move them myself (or likely to be strong enough if it's an adult / teen!)
If phoning 111 doesn't result in good advice on if an ambulance is needed or time to get yourself to a&e, or phone GP, then how are ordinary untrained people expected to always make the right call on that themselves?
Also, whilst again, I of course agree parking difficulties shouldn't in theory mean you call an ambulance, if you desperately worried about a loved one, who is either too young, old immobile or unwell to be 'dropped off' alone, then you do need to factor in if you can get them from the parking to the door of the hospital yourself, and if you are not someone who needs to use the hospital often you may well be unsure of that. I haven't been to a&e for years but as far as I can remember if I had to abandon my car outside the door of a&e, I'd be blocking an ambulance bay or the one drop off point for other patients. And I have no idea if there are wheelchairs I could use from the car park, or any staff around to help.
Even if I did feel I could cope with the parking situation, if I was worried about the person I don't think I'd be driving that's safely if I also had to keep an eye on them. So if I was in my own with someone I was very worried about, I may well decide I had better call an ambulance as not sure if I can safely get them there themselves. Yes you are right that a taxi could be an option, and that's probably what I would do, but again, not all areas get them quickly, some situations, eg blood and vomit I'd assume they would refuse, and they are very expensive and probably don't offer freebies in an emergency!
I'm also pretty horrified by suggestions and stories of people driving themselves with chest pains, head injuries, injuries that affect their movement etc - I'm not sure someone passing out at the wheel or being less able to operate a car normally is something to encourage to reduce pressure on emergency services!
So on the whole, of course people should think about if they really need an ambulance or not, but I have empathy for people who make the wrong call, and think the government shouldn't be blaming ordinary people for their shortfalls!