The different customs and intricacies of friendships and relationships is one of the many reasons why queerbaiting is about marketing and homoerotic subtext is about content.
Japan, for instance, has several different way of saying "I love you" and "you" that help infer the exact nature of the relationship. There's a huge difference between "I love Miku like I love chocolate" and "I love Miku as the love of my life" in the language that can't always be translated with a simply subtitle saying "I love you".
And no relationship is ever the same, some intimate relationships are more physically affections that others, as are some friendships. Lots of teenage girls around here refer to each other as babe. When I was in high school hugging was a big thing and I hated it. Some couples are super lovey dovey touchy PDA, some aren't. Some friends link arms, some don't. Content is very subjective.
Marketing is obvious. You can usually tell if it's a marketing issue, because someone will announce something. Voltron announced Shiro was gay, then gave fandom 0 content but a dead ex and a shoehorned in epilouge. Rowling announces in huge press events about Dumbledore but won't actually give even the slightest hint in canon. Sherlock and Merlin had carefully edited trailers to tease some kind of scandalous situation or potential confessions, often tweeted with the shipping name tag. And the fact that many of these claim they're doing something ground breaking by including LGBT people when actually they're just declaring it, makes it all the more annoying. I mean, if we're just saying stuff and it doesn't have to be in canon, I might as well declare my webcomic is a murder mystery. There is very obvious intent there and not just a bit of dialogue that could imply something.
@JRHoch I've yet to see a show marketed as het that turns out to have no het relationships at all but if anyone spots one please let us know.