If you're seriously asking, how about that unions have consistently and successfully fought for better treatment and pay for workers all around the world. Many of the standards we expect today only exist because of union action over the last century or so.
Developers are no different from any other worker in the sense that they have more power as a group than individually. That generally has translated to better conditions, better pay.
As the gp comment suggests, it seems entirely plausible that this same effect would apply when applied to vendors. A union/guild/group of people is more able to exert influence over vendors than any one individual, and vendors have a bigger incentive to keep them happy and address any issues promptly. Individuals are, as the op demonstrates, completely at the mercy of megacorps.
Organizing wouldn't be a bad idea, a labor union would be.
Trade unions are groups of workers organised around the common cause of improving worker pay and rights.
You said the organised workers part isn't a bad idea, so I have to assume you're objecting to the only other defining feature of trade unions: collectively striving for better pay and conditions?
When an app developer loses Google, they might lose 100% of their revenue (if they only develop for Android).
This fundamental mismatch in bargaining power is why unions are needed for fair resource allocation.
Organizing might be a valid response but a labor union completely misses the root of the issue and would not serve a constructive purpose in this situation.
A trade organization would seem a more appropriate fit than a union.
But you also probably mean "trade association" instead.
Why?
Its a form of insurance.
Your Union will provide legal cover in the event of a dispute with your employer (eg: wrongful termination), legal advice, representation if you are dealing with say, HR department, and are super useful when engaging in collective bargaining to get a better deal when your company starts down the road of stupid policies (eg, limiting WFH).
Think of union dues as a small fee you pay to retain a legal team for employment problems.
I can see the benefit of this if you have absolutely no negotiation skill or even the option to negotiate (i.e. you’re an easily replaceable entry-level worker and your conditions of employment are “take it or leave it”, and you can’t really “leave it”), but in my case, I’m ready to walk at basically any time.
And if I’m ready to just walk away at virtually any time (as a highly skilled professional with more than a decade of experience), I hold all the cards I need for negotiation.
Wouldn’t I be more trouble for the union than I’d be worth?
The doctors, lawyers, actors, musicians, and other professions have guilds like this. What makes them work is that there is a limited supply of available experts in the field, and a desire to raise their bargaining power.