Hopefully if they ever go to Sri Lanka they get localised tuning because I was surprised to find out flashing your lights over there doesn't mean "go ahead", it means "if you don't get out of my way I will ram you"
This is true for India too though traffic there isn't known for its rules.
I hate the countries that do this because it doesn't even make sense as a signal. We already have a horn. They are wasting a channel!
And then there's trucks flashing an indicator to say it's safe to overtake if you're behind them. In the UK it's the nearside indicator, which makes sense: it's a bit like the truck is pulling over to let you pass. In Aotearo, it's often the off-side indicator, so you think the truck is going to pull out in front of you. I've never understood what the Aotearoa drivers are thinking there