To share some insights and info. I pay my assistants $10 to $30 per hour depending on experience and budget. They get paid at end of the day. Any angbao money or tips they get, they keep. Meals are on me, if not provided by the wedding. Morning taxi also on me. They earn more than some 'photographers', plus no commitment, no business risk and no post work.
None of my usual assistants call themselves photographers in fact most of them aren't interested in photography. They are all aged above 30, oldest is 40+. My favorite assistant knows more about off camera lighting than some 'clubsnap-D3s-hobbyists' know photography on the whole. He could setup a 20 person formal family group photo in 10 minutes while I take the time to go toilet. As he measures light with my Sekonic 358 some camera hobbyists thought he pro photog and asked him camera stuff, he donno.
They don't get to shoot - they don't want to, if I get them to shoot, I set all settings for them and tell them the composition and specific things I want and let autofocus do the rest. Out of 50 shots they took, maybe around 10 are ok. I probably use 1 or 2. Their true value is a strong back, carrying 6-8 lenses 4 flashes, 2 lightstands, modifiers, a tripod (yes I old school) extra 1-2 bodies, maybe some MF film gear, sometimes a step ladder, anywhere everywhere I go, leaving me free to shoot without worrying about weight and safety of my gear.
With assistants I hire non-photography people, its personal choice and I know of several other photogs doing the same. Main reason is ethic problems with wannabes. If I need a second photographer, I hire a full time pro shooting for money instead of shooting for portfolio. Usually is a person I know of good moral and business ethics that I can trust. I don't use any random young guy or girl trying to be photographer as I see these as problematic.
If you have no professional portfolio or recommendation/referral from other pro photogs, I doubt anyone serious in the business would risk using an stranger. So it might be reasonable to work for free on a first gig. If they don't call you again, it means you messed up somewhere. If they keep calling you but never pay you, it means they are using you.
Ex-assistants of mine who dont get called anymore usually because of these reasons:
1) Leaving equipment unattended or asking wedding guest/party to help safeguard equipment - wtf I hire them for in the first place?
2) Went missing in the middle - smoking habit usually, or gf/bf problem.
3) Trying to be photographer - self promotion, networking with my clients, ethics problems
4) Drink alcohol at reception - my instruction was if they receive, decline, if cannot decline, accept politely but dont drink, pass back to waiter at first opportunity.
5) Wear wrong attire despite instructions, or poor personal hygiene or unkempt appearance.
6) Talk too much, too loud, and crack jokes with client and client's guests.
Hope this helps.