Advertising alcohol on tv has strict rules around it, when it can advertise and what products can be advertising.
In principle gambling should be similarly controlled. However a recent government paper pointed out that
gambling was a permitted activity and that licensed operators’ ability to advertise was “a key advantage” over the black market. If this advantage was removed, “we would undermine our ability to ensure that gambling is conducted in a fair and open way, that it remains crime-free, and that children and vulnerable people are protected.”
This is a point I had never thought about before. This danger is not present when advertising alcohol, yes, people will buy bootleg drink, but that is a completely different thing.
Remember most, possibly all, unregistered gambling is criminally controlled.