@Background Pony  
Lesson Zero: RD was doing it because she was a friend somewhat and also able to destroy a barn with her Rainboom. Apple Bloom, Big Mac, and possibly Granny Smith were in a clearing near the park.  
Sisterhooves: was an agri-cultural competition dedicated to sisters. Propably paid by the Mayor of Ponyville or the Apples themselves.  
Cider Squeezy: the Mane 6 were helping Applejack mantain the barn as fellow Elements of Harmony. Apple Bloom, Big Mac, and Granny Smith were helping them too.  
Family Reunion: is actually the extended Apple Family members plus Apple Family friends and spouses\partners who are raising a new barn, possibly to replace the one destroyed in Lesson Zero.

The “largest family in Ponyville” is an old mare, a pre-adolescent foal, and two young adults? Ponyville’s in trouble, then.
 
And allow me to address the two episodes that TheDog couldn’t recall: In “Lesson Zero”, Rainbow Dash destroyed an old barn for Applejack, and she did it with such gusto that she probably begged AJ for permission to do it. As for “Sisterhooves Social”, the competitors in the obstacle course crushed grapes into grape juice, a task which kinda pales in comparison to what the Apple family had to do in order to set up the festival on their own farm.

@BP
 
I don’t exactly remember two of them, but Cider Squeezy was the rest of the mane six helping the Apples, most of the town just sat and watched the competition, while Family Reunion was the extended Apple family rebuilding the wrecked barn.
 
And neither time were they “tricked” into doing it without pay. They never expected payment, and chose to do it.

@WatermelonRat  
If it was only for fun, some people believe faithfully on those headcanons, remember how much time people took to accept Vinyl’s canon eyes?
 
Now tell a BP fan that Lyra doesn’t like humans to see if it’s a game to them.

Yet who do bronies drool over BG ponies but hate on Toy only ponies with the same idea, or OCs that fans create 100%?

@Takuto  
Think of it this way: The background ponies don’t have set personalities, so fans make up personalities and stories for them. Think of it like playing with a toy (this show is basically a glorified toy commercial, after all). We like the main ponies, but there’s a more personal connection with the background ponies for a lot of people.

@Takuto  
There are 4 episodes I can think of of the top of my head (Sisterhooves, Lesson Zero, Cider Squeezy, Family Reunion) where the Apples, despite being the largest family in Ponyville, have tricked half the town into showing up at the farm and doing their work for them, uncompensated.

@BP  
You know, hearing this from someone with your name doesn’t help.

@Takuto  
Lyra aside, Applejack is objectively worst pony.

The truth…is out there.
 

@Grieffon  
But what about background ponies like Lyra and Bon Bon?  
They’re overrated to the point i’ve seen someone saying Lyra is best pony and Applejack worst.

v was me.

@Takuto  
To be fair people talk a lot more about other characters than Derpy these days.

Welcome to the fandom. Where one-frame ponies get novels of background and everybody is secretly screwing each other.

Many protagonists to develop, tons of secondary characters to get screentime,  
and yet people fuss over background ponies?

I have a simpler theory… it was for the lols and nothing else (but that’s just my opinion)

Guys…. stop.
 
I did not even expect Derpy to be in this episode at all. She’s not related to the Apples, so why would she go to the Apple Family Reunion… DUH.
 
She was already shown in the Crystal Empire AND Magic Duel (TWICE!)

I need shibas to comment on this.

You are trying very, very hard OP

IT ALL MAKES SENSE NOW :o

My mind has been blown