What do you call e-minor triad containing G-B-E?

[tapper mike]

One doesn't need a 5th for the 6th to be present. And If you are tuning a guitar to standard tuning it's less common to have a chord voiced with both the 5th and the 6th

scroll to the 10:37 marker where Duke Rolibard starts discussing "Chuck Berry Sliding 6ths chords"



It's the same 1-3-6 spelling found in countless songs from jazz to blues to rock to country to funk to reggae

[Sascha Franck]

if it's really got to have the fifth and the sixth it's *add 6*,

Wrong.
In contemporary analysis, you can also have a 4-part chord that is called "6" only. It doesn't exactly matter whether the (obvious) 5th is played. In addition, in contemporary harmonic analysis, the 6th isn't replacing the 5th but the 7th.
Someone as clever as you should know that, no?

but a lead sheet, fake book, big honking diff between Em/G and G6, eh.

No. And I didn't say so, either.
Yet, in case it's showing up in an Emin context, it's called Emin, in a G context it's called G(6).
And well, following your logic, as soon as the inversion would be BEG you'd probably call it Bsus/b6 or something, huh?

you just implied the guitarist may as well ignore the voicing...

And that is absolutely what's happening in a lead sheet context. You trust the guitar player and he/she will find the best voicing. It's even exactly like that in big bands, where almost any note is written down.

- SF