I suggest Mailbox is an example of a poorly structured (and therefore less trustworthy) team.
Also, the size of a team may not matter if the leader doesn’t involve others in the decision making processes. I know I’ve been quite critical of Mailbox, but I think they may be an example. Their guide seems written by one very well knowledgeable guy (Sir Mr expert Heinlein) but not proofread by the people who need the guide (causing A LOT of confusion). Their news lists his media appearances, but no sign of other staff. And he responds to people in the forums, often in quite a dismissive manner to reasonable criticism of the service. Unlike its competitors, their website does not reveal the identity of any employees besides the leader. Proton lists many many directors and managers. Posteo has three people (two of which a couple). Tutanota has a paragraph on the whole team, but the hierarchy is unclear.
I mean to no harm to Mailbox or to Peer Heinlein, who I feel like I’m criticizing when I criticize Mailbox, which in itself I consider to be criticism of Mailbox (but I hope not Heinlein). But trust is too important in the case of email for me to ignore my doubts about Mailbox.