The general attitude is because its a public service, you shouldn't be bothering the hospital unless you are really sick or badly injured. If it can be treated by out of hours or GP then it should be. Also you dont get much in the way of complex testing unless you push for it. I have a chronic problem with my skin which causes dry eye, and has led to scarring on my cornea which could blind me, still the NHS acted like I was wasting their time for ages.
There is a non emergency NHS line which can be called and they will advise if your symptoms are something more serious in need of immediate attention/a trip to A&E. They usually look for a reason not to send you to hospital, unless its just that serious they have to.
Going to the ER when you feel you are having a medical emergency is what the ER is for. If the doctors need an ECG and blood test to determine whether I am having a heart-attack or an anxiety attack then how should I know if what I am experiencing is life-threatening or not? This is why Munchies have it so easy, because doctors do not always know whether it is serious or not without doing necessary tests.
Common somatic complains like chest pain, tachycardia, shortness of breath, dizziness, hyperventilation, nausea, headache (and even seizures) could just be anxiety/somatic OR they could be acute heart-failure, fulminant myocarditis, malignant arrhythmia, hypertensive crisis, pneumothorax, a lung emboly, acute lung injury, status asthmaticus, (newly onset) epilepsy, sepsis, poisoning, thyroid storm, encephalitis or stroke. All potentially deadly conditions. Most people with anxiety can distinguish most of the time, but not always. 9 times out of 10 it might just be anxiety, but this one time it might be the actual thing because the symptoms are just so bad or because they are new symptoms.
I think people who do not have (health) anxiety or a somatic disorder have trouble understanding that yes, the symptoms can be that bad. If laymen could easily distinguish these symptoms from an acute health crisis then no one with a panic attack or anxiety would ever end up in the ER.