I don’t think this is the intended answer, but it fits quite well:
I am a staircase, covered in paint.
The stock market is frequently represented as candlestick charts with look like green and red stairs
Each step taken gives knowledge, new and quaint.
Each new market move reflects an immense amount of information absorbed.
I used to be more of a ramp type shape,
Because of exponential growth, longer term charts look like a ramp
But progress was slow, like rewinding a tape.
Slower in the past because of exponential growth and tape is a very common market term for the list of prices
My new inside is famously difficult to place,
Modern markets are electronic and located in different areas around the globe, their placement and one’s computer’s position relative to them is of great importance to modern trading
At least if you look only at my face.
This one I can’t place
I contain the world and all of its gain,
The Market represents the global economy and literally all of its gain.
And delineate most of its struggle and pain.
You can look back and see market crashes and times of economic crisis and difficulty
Something I can understand, being myself bound.
Bound by the physical limits of labor and production, supply and demand.
So, stranger, who am I? Can my name be found?
Be observant, omniscient, keen,
And I will show what has already been seen.
Feels like this clue means that the name is hidden cleverly in the puzzle, but I haven’t found that