Context and purpose have a lot to do with the reasons things are blurred for legal reasons. You (royal ‘you’) can try and infer why it happened from a situation, but you may not be right.
A common one in Australia is that the ABC, our national broadcaster, can’t be seen to be promoting commercial third parties, a point enforced with some probably semi-complex legislation, and/or in their charter. So in a lot of their in-house factual/science programs, logos are blurred on computers (e.g. Apple symbols on laptops) or products when they appear. But not all. It depends on what’s seen to be happening in the program, the message conveyed and what the subject matter is. And again, this is ABC-specific.
If you think about the purposes of trademarks as intellectual property, questions you can ask yourself in terms of ‘what’t the likeliness of aggravating the trademark owner through this image’ include - does it look like you’re explicitly leveraging someone’s trademark for your own gain (of any kind)? Could you intentionally or unintentionally be seen to be deceiving someone into thinking the trademark owner is affiliated with you, or endorses what you’re doing? Are you adding a ton of value to your image (e.g. massively increasing the chances people will be interested in looking at it) by including the trademark, that you wouldn’t get without having the trademark present? etc. In the case of casual inclusion in a photo, the answers will usually be no.