Similarly to how a party's representative is often referred to in the third person as "solicitors," it seems often that in legal submissions and other correspondence, individual solicitors will use a first-person plural as well, a kind of "legal 'we'."
What is the basis and significance of it, and when is it appropriate? Is it understood to reflect that an entire firm (and so team) of lawyers perhaps, to some degree or other, collaborated to arrive at the conclusions contained in the correspondence, thus lending them a greater credibility and kind of clout? "We submit" "We contend" "We believe".
Warren Buffett's famous shareholders seem to do the same thing, but that seems more easily explained by the fact that the letter is to shareholders, and so inherently, the relationship of a shareholder with a company is very specifically with the company itself, on the behalf of which Buffett would then necessarily be writing, so we could be understood to encompass all of those who make up the company.
One also recalls the conventional "royal we," where monarchs (and perhaps some other nobility?) are conventionally entitled to refer to themselves in the plural.