Sure, why not. If it is a really life or death emergency you of course need to call an ambulance which I'll assume has license to do things illegal for you to get there faster. Most ER visits are important to soon, but few are now important.
By your methodology everyone visiting an emergency room on a typical night should call ambulance because the cars have been banned in the city ? I know for sure as heck they can walk or ride a fancy electric bike.
No, most people don't need an ambulance because they can walk in to the ER. That doesn't mean they shouldn't be in the ER, just that an extra hour walking there isn't going to matter. (in hindsight 80% shouldn't be there, but the symptoms of something that needs to be handled now and a trivial ache are generally the same so you go just in case which inflates the numbers)