The problem with early merges is that there's no way people that merge in are at highway speeds when they merge, causing everyone behind them to have to slow down, which eventually can cause traffic jams. Just use the whole lane, make SURE you're going the same speed as the rest of traffic. The confusion there is that because of an existing jam or slowdown, people are already at a matching speed at the start of the on ramp. Or so they think.
>The problem with early merges is that there's no way people that merge in are at highway speeds
If you drive anything reasonably modern and not grossly overloaded/under-powered you can plant your right foot and be going traffic speed (or close to it) by the end of all but the smallest on-ramps. Most traffic is not made up of box trucks and panel vans so there is no technical limitation that prevents zipper merging on most on-ramps most of the time. Going close to traffic speed makes it a lot easier to merge but a lot of people aren't comfortable doing it that way.
I didn't read this as applying to 'on ramps' (we call them sliproads in the UK) that are lanes merging onto a highway/freeway/motorway. It wouldn't make sense under any circumstances for people on the highway to slow down and stop to let traffic join! I think this is referring to two 'equal' lanes of one road that become one — and, thus, merge. I don't know if they're unusual in other countries, but they're definitely a thing in the UK.
