Financial companies have taken and upgraded/invested in microwave links because they can be comparatively economical to get "as the crow flies" distances between sites:
I'm not sure about the high packet loss statement, but it wouldn't suprise me that it's true if the latency is lower enough to get to take advantage of arbitrage opportunities often enough to justify the cost.
https://www.latimes.com/business/la-fi-high-speed-trading-20...
https://arstechnica.com/information-technology/2016/11/priva...
https://en.wikipedia.org/wiki/TD-2#Reemergence
I'm not sure about the high packet loss statement, but it wouldn't suprise me that it's true if the latency is lower enough to get to take advantage of arbitrage opportunities often enough to justify the cost.