By that logic everyone in Thedas submits to Orlais because they have the most power in the known world. Loghain would probably prefer to be able to march to Val Royeaux and take a dump on the Imperial Throne, but he can't, therefore Orlais rules over Ferelden.
City Elves are part of a power structure where they are officially second class subjects to humans. City Elves are legally subordinate to human masters within their own society. Dalish aren't because they are outsiders. They are lead by free mages. They can travel where they want. They aren't subjects to legislation that applies to city elves. The City Elves accept that they are servants to human Lords. Dalish Elves are outside of their jurisdiction. Templars tend to avoid taking in Dalish Keepers (even though they are supposed to by law) because fighting through an entire clan is impractical. If Dalish are attacked they can fight back. And they structured their society in such a way as to adapt to the threat of the humans superior millitary. Being weaker than another nation doesn't make mean they rule you. Avoiding them doesn't mean they rule you. Adaptation is not submission.
Anybody who attacks a group of villagers is going to face consequences. Everyone anywhere is subject to cause and effect. But you don't say they are "subservient" to outside factors. Dalish culture isn't based on the desire to fight and reclaim the Dales. It's about staying alive and independent, which they are.
Ferelden can't compare to the Dalish: they evicted the Orlesians. They were conquered, occupied, and forced them out through military force. The Orlesians haven't returned since that time. Ferelden took its land back, reasserted its culture, and forced Orlais to back home. It's not about preference. It's about power. What Ferelden did is called standing up. What the Dalish are doing is called bending over.
CEs aren't legally subordinate. That slavery, which we know doesn't exist. They're second-class citizens because of the power structure. We know this from Magistrate's Orders questline in DA2, where the CEs are clearly the beneficiaries of the same legal system that's applied in a racist way. Like it was IRL against minorities a long time ago, and still is in some places, even in the West.
The Dalish can't travel where they want. What happens if they travel to a human village? Can they go shopping in Denerim? What if they want to buy some grain in Lothering? Can they book a ship from Gwaren to Kirkwall? No, they can't. They can't freely travel anymore than a fugitive is "free" to travel. Their freedom to travel is simply to stay outside of the sight of the humans. The CEs can freely travel too - we have plenty of examples. There were CEs going to join the host in Ostagar. In Kirkwall, the CEs from the Magistrate's Order quest were not only wealthy, they clearly and freely able to leave the city. The CEs that go from Alienage to Alienage to get married are clearly free to travel. The Alienage Culture codex outright shows what you're saying is false here:
But don't be so anxious to start tearing down the walls and picking fights with the guards. They keep out more than they keep in. We don't have to live here, you know. Sometimes a family gets a good break, and they buy a house in the docks, or the outskirts of town. If they're lucky, they come back to the alienage after the looters have burned their house down. The unlucky ones just go to the paupers' field.
The problem here is racism, but it's not unequal legal treatment nor is it the legal restriction on their ability to travel outside of the alienage.
You say that the Dalish are free from human laws - they're not. If a Dalish walks up to a human in the middle of a city and stabs them in the throat, they're taken in for murder. They're as free from human laws as a large bunch of brigands are - they're free for so long as the humans aren't going to move in military force against them.
Your own example of what the templars do is the best one - they clearly and categorically assert their right to capture Keepers, and the only reason they don't is because of the military effort involved. In DA2 when they're seeking Feynriel they capture and torture hunters, and they're about to kill another group of hunters unless Hawke intervenes.
Avoiding them is submission. They rule you. They define where you live. They define how you live. They define where you go.
But you don't say they are "subservient" to outside factors. Dalish culture isn't based on the desire to fight and reclaim the Dales. It's about staying alive and independent, which they are.
That's what the CEs are doing. They're "adapting" to the humans, and they're "staying alive" by keeping their head down. The Dalish just do it from further away and pat themselves on the back each time they run away from humans.