I'm not an ER person, but just wanted to weigh in here. I see both sides to this discussion.
I think you misinterpreted me, because there aren't really two "sides". I am strongly in favor of getting students 'real world' experience, and a student should want to be in a facility that will give them as much learning as possible. And it is very reasonable for a student to ask "how much will I be involved if I'm at your facility?" Two points of clarification:
1) The OP is looking for experience 1-3 years, not a 4th-yr externship, which is different because of the different level of experience/knowledge. For example, if I'm comfortable with a student and see that they are prepared/knowledgeable/etc, I'll happily let them scope a gastric foreign body with coaching. I generally wouldn't let a 1st- through 3rd-year student do that.
2) I have had a few experiences with students who seem to think that a functioning hospital's highest priority should be them, and that the entire time they are there should be centered around them and their learning. That just isn't going to happen - a hospital's priority is to its patients and clients first and foremost, and any teaching has to happen after those priorities have been fully met. Ideally, teaching happens alongside it, but there are times where a student simply can't be in the middle of things. Whenever I see a student talk about wanting a place that will "not only welcome externs, but actually like to have them around and want to teach them" it sets off just a little alarm bell.
That doesn't mean the OP would be like that. I don't know the OP, and he might be amazing. It just means that when I've heard similar things from students, I have occasionally had bad experiences, and I wanted to make sure he considered the perspective of the host facility.
My philosophy when students are with me in the ER is - the more you've taken time to be prepared, ask good questions, show interest, etc., the more 'hands on' I'm going to get you.
When a student and I come back from an exam room and I say to the student "Ok, talk to me about the case. What are you thinking, what's your differential list, and what dx do you recommend?" .... if they can't start saying things that are remotely reasonable (and I sure don't expect them to have perfect - or even great - answers), then you can bet it will limit their involvement.
If we have a 2-year-old male neutered cat who has been in/out of the litterbox unproductively for the last 14 hours, vocalizing, and has a big hard round lump in the caudal abdomen .... and the student can't get "urethral obstruction" somewhere on their differential list .... there's not a chance I'm going to let them unblock it. On the flip side, if the student says "well, this is almost definitely a UO, other differentials would include <blah>, I'd like to do some bloodwork, maybe rads and/or ultrasound the bladder/urethra, and if it still looks like a UO, hospitalize it for unblocking and fluid therapy. Oh, and can we please give the cat some buprenorphine?" .... well damn, that student is going to get to unblock the cat and write up its treatment sheet, because they just aced it. That's also the student I'm going to have talk to the owner about FLUTD, the underlying causes, short-term and long-term therapy, etc.
Bottom line: These are real patients, not a classroom. I will let a student do almost anything so long as the student is prepared and demonstrating competency, but my patient is more important than the student. Any place where that isn't true is a place I wouldn't want
my animal treated.