Well, on a technicality a 'like' is a counter in a computer somewhere and the bits to count the 'fake likes' are the same bits used to count the 'real likes'. By the time the number of likes is displayed they are to all intents and purposes indistinguishable and identical in every respect.

The failure is on Instagram in not being able to separate out the fake likes from the real ones before they increment the counter.

I'm a little confused because you argue all likes are the same and then make the distinction between fake and real likes.

It's prior and post accumulation in some counter or for display purposes. So at the moment the like is done it is possible to distinguish between fake and real but after you collapse them into a single counter you no longer can distinguish fake and real.

This is what gives the 'fake likes' their value, that they are then used by Instagram in exactly the same way as real likes. Instagram clearly fails at distinguishing the two, so you really can't fault the users for not being able to do so either. The fact that this service is available and apparently works is a pretty strong bit of evidence that all likes should be distrusted but that's not how it will play out.

But is this just a dumb counter though? Instagram shows the list of people who liked a photo.

Say, if one of my friends has a picture with 5 likes from people I recognize, and another friend has a photo with 100 likes from weirdly-named accounts, I can tell which ones are fake.

real likes = unpaid fake likes = paid

likes are a proxy for consumer interest. kind of how survey's where the respondents are paid to agree to something aren't valid measures of opinion.

I just mean: whole of that 'likes economy' is a scam from top to bottom. You don't become much more unfair for just buying them, because nearly all other ways of getting likes that potentially have positive ROI aren't too far from this.