I can think of numerous reasons why an Open trader might choose to run rather than submit to demands.
- "Don't reward the terrorists, it only encourages them". Spend millions on rebuys, not one cent in tribute - that sort of thing. In other words, they're RPing a character who refuses to give comfort to criminals, even at personal risk and expense. I never play in Open, but if I did, I would definitely play this way; it's how I play against the NPCs. No criminal scum is getting one rusty scrap of biowaste out of my cargo hold.
- Perhaps the last time someone interdicted them and issued demands, they were blown up anyway for the LOLs, even when they complied with the demands. Let's call this option "experience".
- A variant on the second reason above, that they may be so busy g out and trying to escape that they aren't really paying attention to anything in Comms.
- The interdicted player may not be speaking the same language you are, and/or may not be familiar enough with the language to understand any unusual jargon or abbreviations you may have used in your communications. Especially if you're going the full talk-like-a-pirate RP.
- They may have accidentally hit "Open" instead of some other mode and never noticed the potential danger until too late.