On the titular question, I would say that there’s a realm in English where it’s possible to omit the subject. However, it is generally considered necessarily terse and wouldn’t be suitable for general conversation, due to distilling the language down to what essentially is a series of verbs strung together. That realm would be commands or instructions, with the specific example of highway/motorway signage.

It’s a unique challenge for English highway signs, to convey exactly what’s important but also not be too long to read. There is a physical limit for why “DO NOT ENTER” is preferred over “Automobiles May Not Turn Right Onto This Road”. In the UK, they even reduce this to “NO ENTRY”, which is in line with the pattern of “no parking” or “no lorries over 3 tonnes”.

Even more reduced are the words “EXIT ONLY” which means “this lane will soon terminate, vehicles in this lane will be forced to exit the highway, and vehicles should change lanes to remain on the highway”. All of that is from the very context of a road, made common through the context of driver training, signage, and lane markings.

This is one of the reasons why a language like Japanese gets “lost” in translation

I would argue that translation is not the exercise of converting words like-for-like, but to convey the same meaning or experience in the target language. As an example, expletives in other languages will reference different things, be it name-calling or dishonorable comparisons in Japanese, genitalia in English, excrement in German, etc. But there is no requirement that a mild expletive in Japanese needs to be perfectly preserved into English. Rather, the overall work when read in English should use an equivalently mild expletive, with proper consideration for what the original audience was. So if the Japanese source was a children’s anime and light high-school insults are in the dialogue, the English translation might render this as minced oaths in English. The character building should be mostly identical for the English audience.

But done only mechanically and without artistry, such a translation is going to sound very “American” and lose much of the soul of the original. IMO, this is something that older Crunchyroll translations suffered from, and fansubs did a much better job of preserving the dialogue faithfully. Even while doing this, some parts of the language are necessarily untranslatable, since things like post-nominal honorifics don’t exist in English. As a result, some fansubs might stylistically choose to always render the honorific every time – eg spelling out Kami-sama rather than translating as God.

This is in tandem to other subtitle-specific considerations like keeping the surname-then-given name ordering, so that the subtitles read in the same order as they are spoken in full (eg Kudo Shinichi) and correctly shortening to just the surname when addressed as such (eg Kudo-san or Kudo-sama).

Even still, it could be acceptable to translate as “Mr Kudo” or “Master Kudo”, if that’s the vibe that the source material was going for. Translation is, as I understand it, a holistic work. And perhaps the best example I can cite to is the English translation of The Three Body Problem by Liu Cixin. Ken Liu did the translation, and made an explicit choice to hew towards Chinese terminology, explained in footnotes, because the ordering of the cosmic velocities (first, second, third) is more clearly a stair step towards space travel, rather than using the typical terms of “orbital velocity” and “escape velocity” in English.

The English translation intentionally makes itself clear as a translation, but care was taken to make sure it is uniquely from eastern source material yet still perfectly readable in English for someone that knows nothing of Chinese 20th Century history or much of anything about space travel. In that sense, it is accessible sci-fi, where even us Americans will understand the great work that Liu Cixin set into ink.