I think the original topic was on how difficult it was to get an anesthesia residency. I am not sure why ER docs and Surgeons are interested. Here is my opinion.
It can vary quite a bit. If you want to get into a top tier program, yes it is hard. At the same time, there are less competitive programs that are not so diffucult to get into. Some of those programs are still good training programs, some are not. If you are not the strongest candidate, choose a mid-level and a top-tier program and do a rotation there. You may not have the best grades, but if you do your reading and know you stuff when you are there, those programs can see your good points. That way, when the match comes around, they may prefer to take somebody who they know, though, they have lower grades, versus an unknown with higher grades/scores.
Don't make your choice based solely on how competitive residencies are, nor should you make it on how the lifestyle is during residency. Family med is a cake residency, but you will have to work like a dog to make 200k once you get out. Surgery has traditionally been a miserable residency, but once you are finished, you can confine your practice to breast or hemorrhoids and never take call (do all you cases at a surgery center.) The same goes for many other specialties. Some, such as CT surgery suck both in training and out.
Anesthesia can be an 80 hour a week job or a 10 hour a week job. I have friends I trained with who are doing mostly cardiac/transplant. They work crazy hours, but they do many complex procedures/cases and like the challenge. Other people I know do pain, while I have friends who have ASC jobs and work 35 hrs/week with no call. Of course, the pay corresponds with hours.
Do something you like. I hated clinic and like the OR, pharmacology, and procedures. I chose anesthesia. I looked at ER, but it is mostly clinic. I also like to make money. Anesthesia has been very rewarding. I do quite a bit of acute pain with indwelling nerve catheters. It is great to see somebody after a knee replacement who has zero pain. Especially after they had the other knee done at another hospital and were in terrible pain. Choose wisely, it is tempting to coast during your fourth year, but I would recommend to use it to be certain about your specialty choice.