As one who grew up on a farm and used to do a load of hedgelaying myself;
The process is this- plant a row of hawthorn; leave it for 5-8 years. Lay it. Keep it trimmed with a flail. (Which would have been done with slasher or bill hook.) If the hedge is overgrown, take the side off with a shapesaw and lay it- probably needing a chainsaw and a lot of thinning at this point! In both cases, a well established hedge is maintained by flailing it every year or two, so it remains dense and close growing.
It makes me laugh the ignorant sh*t a lot of people spout- I’ve had people complain about us doing the latter, even though the end result is a far better wildlife corridor and healthy hedge. Likewise complaints about pollarding willow trees, even though established pollards will end up splitting their trunks if not cut back…
The timescale of these processes is a tad longer than someone trundling down the road on a bike for 10 minutes, on half a dozen occasions a year…
Edit- as above, hawthorn is a sod to work with- goes right through any glove, especially when it’s older! Makes for great firewood though…