I've never seen a knife like that where I live, in California. The only small serrated knifes people here have are stake knives and on rare occasions sausage knives.
It's strange how two relatively similar cultures can have such oddball differences.
This is while living in California's Central Valley, where a third of the world's tomatoes are grown, so it's not like tomatoes aren't a major part of the culture here.
I wonder if it's because most of California's settlement was within the last 200 years, with modern metallurgy making it common for knifes to hold their edge long enough to easily cut tomatoes with only occasional sharpening, negating the need for a special knife just for tomatoes.
Nationwide advertisements for knives show people using straight-bladed knives for cutting cucumbers and tomatoes, despite stated stake knives being extremely common, so tomato knives are likely rare throughout the country, not that much of the country is any older than California.
You can't sharpen a serrated knife, though. When it becomes irritating to cut tomatoes with my straight knife, I know it's time to sharpen it—that's how I avoid getting used to a dull knife.
It’s kind of tedious, but you can do it with a tool like the DMT Diafold Serrated Knife Sharpener. On most serrated knives, you will also want to lightly sharped/deburr the other face at an extremely shallow angle using a whetstone that either you don’t care about too much or that is extremely resistant to scratching (e.g. a DMT-style flat stone). If you do that part on something like a traditional Japanese stone, you will make a mess.
