In my experience the only way to capture all digital from DV/HDV is via Firewire. Even the DV cams that included a USB-out could only transfer stills via USB. Maybe there were some high end HDV cams that could record DV/HDV to an SD card, but I don't recall ever seeing one.
There are some devices on the market that will convert video and transfer to a computer via USB (Vidbox being one of them) but every one I know of requires analog a/v input. Worse, most use composite video as input, not S-video or component video (composite is lowest quality but if it's all you have, it's what you have to use).
Blackmagic used to have a converter called the Intensity Shuttle, which could connect to a Mac via USB or Thunderbolt, but it was discontinued some years ago ... it had both HDMI & analog video in (composite, S-video & component). But although HDMI is a digital input, there is no way to use it for DV, so you were still stuck with analog in.
My suggestion for people who do not have the necessary Firewire capabilities is to use a video transfer service. Most charge around $15/DV tape (1 hour video) to transfer to DVD or hi-res MP4. Some services even offer a range of different codecs & formats for conversion.