There are several classes of people who “present” at scientific conferences.
There are students/trainees/lower-level faculty who might for example do a poster presentation or a minor talk at a conference and pay a registration fee, often being reimbursed for that and other expenses by their university or med school.
Conference speakers, especially those with strong reputations in their fields, frequently are paid and/or get their registration waived by the conference organizers.
Being an “invited speaker” as in Kelevra’s example might not necessarily get you a fee for your presentation, but it seems odd to me that a conference would hit such an individual up for a big registration fee. It makes me wonder if “invited speakers” are mainly a cash cow for organizers of certain conferences, like authors are for predatory journals.
The conferences I have been a part of planning, or people I know who have been invited speakers, typically do have to pay the registration fee (which is usually a more expensive one than students because they’re usually faculty) but get a honorarium or stipend later which is in excess of that.
Our invited speakers are often in sessions set up because we didn’t get enough good papers to fill up the program, and sometimes because we decide to highlight an up and coming topic which is too new for getting lots of papers. The speakers are vetted by the committee. Full disclosure: I’ve been an invited speaker a few times.
Keynote speakers are given special treatment. Not paid, but they do get free registration - not that they stick around - and travel and hotel is paid for.
In the good old days when we had a big exhibit floor which made us lots of money speakers got free registration. A lot depends on how big and profitable the conference is.
And on the expenses for the conference. Something that’s taking up a big-city conference hall will have more expenses than something that’s done in the appropriate department’s lecture halls at the University. And that’s before questions like whether rooms and meals are part of the conference fee or not.
I don’t think I’ve ever seen a conference where rooms are included. Meals, sure. That would penalize local people who don’t need a room. That even goes for workshops located in the middle of nowhere where there weren’t alternatives.
BTW, conferences get kickbacks for hotel rooms its attendees book. Reasonably big ones. So those who book in other hotels, often because they get a better deal from work travel agencies, hurt the conference budget.
Universities are cheaper for small conferences where there are enough nearby hotel rooms for participants. For big conferences with parallel sessions you need to have the rooms near each other so people can session hop. And of course universities can’t handle exhibits.
You don’t need a convention center, many hotels can handle reasonably sized conferences. We were in Disneyland for years.
I’ve never personally been to one where either is included (aside from pastries and coffee outside the presentation hall in the morning), but it seemed plausible enough that there might be some where they are, and that would naturally increase the cost. Especially given
which means it would make sense for them to bundle the rooms in.
The reason lunch is included it to keep attendees at the conference site. Force them to go outside, and you might lose them, especially if you are in an urban area. You might also have trouble getting them back in time for the next session.
We have our lunches served on the exhibit floor (they are not fancy) to encourage attendees to visit the exhibitors.
Then you have to worry about no-shows and those who want to leave early or extend their stays. Much easier for the hotel to do it. Plus the attendees get their points with the hotel if they book directly in the block. It also gives the option of grad students sharing rooms, going to cheaper hotels, etc.
It might also make the registration costs look much bigger. Same amount, but it might be more palatable split into two transactions.
The ultimate was when we were in the Santa Clara (CA) convention center. That was owned by the county, so we got credit for all hotel rooms booked by attendees in the county, not just the convention hotels. We contract out the job of dealing with hotels, but we have people working with our sponsoring organization doing contracts. We co-located with another conference once, and found that they didn’t negotiate either kickbacks or free rooms for steering committee members. I was general chair in Santa Clara and got quite the suite - funny since I lived half an hour away.