I think the difference is that many companies in LA are smaller and independent, but I caution that anyone who thinks that Hollywood is more than a small fraction of Los Angeles work hasn't explored much of the city. E-commerce and random website dev is also a much larger market than any town I've seen.
Another problem is the shear size of the city and the accompanying suburbs. You have tech in Pasadena, Burbank, Santa Monica, Torrence, etc, and no sane person would make these cross-town drives every day. I don't think that many people who live in LA even realize how large the place is, and possibly wouldn't realize that many "cities" aren't cities at all, but a part of LA.
In my observation, there is more tech work in LA than Austin, but I digress.
In 2014, New York City had 165,300 finance jobs (NAIC code 523) and 365,500 tech jobs (541), broadly defined [1].
To illustrate why this article's metric is silly, consider that in 2014 about 4.1 million people were employed in New York City [2][3]. Thus 4% of employees worked in finance and 9% in tech. Hoboken, New Jersey, meanwhile, had 34,054 people employed in 2014 [4] and, in 2015, about 7,300 employed in finance [5] (22% of total employment). I guess we should crown Hoboken, instead of New York City, as the nation's new financial capital.
[1] https://www.labor.ny.gov/stats/PDFs/Significant-Industries-N...
[2] https://www.bls.gov/regions/new-york-new-jersey/data/xg-tabl...
[3] http://www1.nyc.gov/assets/planning/download/pdf/data-maps/n...
[4] https://datausa.io/profile/geo/hoboken-nj/#category_industri...
[5] https://datausa.io/profile/geo/hoboken-nj/#category_occupati...
But in the end, it's the country's third largest city, the metro area is huge, and tech is just one industry of many. The number of jobs may be large, but the percentage will never be as high as with small, specialized towns.
Those metrics can be misleading, though: if you want to change jobs, you care more about "total number of other interesting opportunities in this one field" than "number of opportunities in this field compared to other fields."