"Do you like cameras?"
I think the difference is between the topic and subject. Cameras as a topic would mean "do you like cameras in general" or "as for cameras, do you like them" whereas as a subject you might mean "do you like the camera" or "how do you like this camera". Topics would be for general references and subjects would be more for specific objects. A good one on another lesson was vegetables. Yasai wa sukinai would mean I do not like vegetables whereas yasai ga sukinai would mean i dont like these vegetables (maybe in front of you). One implies that you think vegetables suck and the other implies that maybe these vegetables may have been prepared badly or werent the type you like
i think the first part of this is right. は can be used make contrasts. For example if you say あなたのシャツは好きです it sounds like, " i like your shirt.. but not your pants or something else" , it comes off as more of an insult. But here it could be "do you like cameras or maybe you like a different hobby or you think cameras are cool but dont have one etc" source: https://youtu.be/qrjHT8FAuWY
(As for you), do you like cameras?
I think this is more like we were already talking about cameras, so I changed the topic to "you" and asked if you like cameras.
(As for) cameras, do you like them?
I think this would be the case if no one had brought up cameras previously. So the topic is introduced with "カメラは".
I believe は and が both work here, since no context is provided. Maybe someone who knows better can confirm.
On this construction, i know other more 'formal' courses always use 'ga'. I will add that although I have found Duo to use 'wa' perhaps in excess, I am also aware that having looked for specific rules on the use of 'ga' and 'wa', is very apparent this is a source of confusion for the japanese and explantions differ widely from course to course. The added confusion at least for England english is the japanese refer to subject and topic and we refer to subject and object. In english only, subject and topic ARE the same. Do note that 'ga' and 'wo' are regularly interchangeable and wo is used a lot by Duo which fine.
Here's a detailed video on "wa" and "ga", including examples on what is meant when wa is used instead of ga in certain contexts. Can't remember if it explained scentences like this one specifically, but it made me understand these particles a lot better anyway :)
"Ga" is used to to mark subjects, or when something is out of your control. Like when we say something exists we say "があります" when we like something it is beyond our control, or so the East sees it. When asking if we like something though "ha" is used to emphaticly ask we like something specifc, thus we are showing that X is the topic of conversation. "何のスポーツは好きですか" "野球が好きです"
The particle should be が. In the listening comprehension questions they get it right. It's strange they didn't fix that. It also bothers me that in other "put the sentence together" questions the voice pronounces some Kanji in their alternate ways and doesn't change hiragana to fit how it should be pronounced in the sentence (such as hi to bi)