Question: I've seen Facebook's APIs that will sometimes start with resource id. Also, if the URI is for a business process as opposed to a fine grained resource, would it be acceptable to start the endpoint with an ID, e.g.

```
/{fine-grained-id}/businessProcess

```

So the ID does not represent an item in a list of business processes, but is the key resource ID needed for the process.

Answer: 
Roy Fielding introduced REST - <https://www.ics.uci.edu/~fielding/pubs/dissertation/rest_arch_style.htm> - and I don't believe there's anything in his dissertation prescribing a particular URI scheme. As long as your scheme is consistent it should be fine. It would also be advisable if it makes some kind of sense to users why the structure exists, even if it's not a public API.
A key tenet of RESTful interfaces is that they: identify information. 

For example, if you wanted to READ information - e.g. User 123, then you should send a GET request with the id as 123.

Where the ID of the user is located, within the URL, is immaterial. Generally most routes specify the ID at the end of the URL. But you can certainly specify it where ever you like. You don't even need the http protocol to make a restful interface. so long as you can identify the resource - whether at the start of the uri or at the end - it doesn't matter.