It would be incredibly unfortunate if this were found to be illegal. You take many of the same health risks when eating at a friend's house. The only difference is you don't pay your friend.
The exchange of payment is precisely what makes this endeavor subject to food safety/preparation laws and (in many jurisdictions) illegal. It changes a social event into a commercial transaction: you pay someone else to eat food they prepared.
This is not remotely the same thing as friends splitting up the cost to buy food, or reimbursing one friend for purchasing food for a social gathering. We don't regulate social gatherings between friends because they have other means to deal with issues that could arise, even, if necessary, the tort system.
There are different expectations when dealing with commercial food transactions--and some of the major expectations are that the food be safe and prepared safely.
Without judging if it's a good thing or a bad thing, some of these services (e.g. Lyft in some cities) use "suggested donations" instead of payment. It changes the legal & tax consequences.
No, it really doesn't, especially not for tax purposes.
The law (and especially tax law) looks at the substance of the transaction, not its form. Calling a payment for commercial services a "donation" doesn't make it a donation. If it did, every business would ask for "donations" instead of payment. Indeed, as a matter of tax law, calling the Lyft fees "donations" actually makes it worse for the drivers--they can't offset the "donation" income with their Lyft-related expenses. (Lyft can't recharacterize the donations it receives on behalf of the drivers as fee compensation when it remits payment to the drivers because it takes the position that they're independent contractors and it is merely acting as a collection agent.)
It seems that the real safeguard in all of these "sharing economy" things is the transaction record. If someone screws someone over on, say, airbnb, there are bad reviews etc. Maybe bitcoin's mechanism can be used to build public irrevocable reputation around these sorts of things. Different world than having a mediator like airbnb choosing the reviews to publish.
This is not remotely the same thing as friends splitting up the cost to buy food, or reimbursing one friend for purchasing food for a social gathering. We don't regulate social gatherings between friends because they have other means to deal with issues that could arise, even, if necessary, the tort system.
There are different expectations when dealing with commercial food transactions--and some of the major expectations are that the food be safe and prepared safely.