HFT already uses HF radio bands between the UK and USA which is lower latency than either submarine fiber or starlink will be. Although much more limited in kbps.
Big ass yagi uda antennas in certain locations with totally custom rf chains and modems.
Experimental licenses so far or straight up illegal, they're making much more money than any FCC fines would be. The FCC enforcement bureau is actually pretty small and doesn't come after you until you really screw up someone else's pre existing licensed service.
All FCC fines are public info (called a notice of apparent liability and published in their daily data dumps), I've yet to hear of one getting fined.
Big ass yagi uda antennas in certain locations with totally custom rf chains and modems.