Because most sensible people at the senior end of still being "on the tools" take one look at the amount of hours junior managers routinely put in, and also being expected to be available 24/7 for a fixed salary - and they decide they're better off staying hourly paid and doing the odd bit of overtime. £38k, say, for a 38 hour week plus O/T at premium rates is a much better deal than a £40k management salary for a "standard" working week that actually ends up being 60-70 hours. You do the maths who gets the best hourly rate, and who has to put up with the most shite. Hourly paid you can walk away from all the crap at clocking off time and forget about it until your next working day. Junior management in many organisations are just expendable cannon fodder, and largely used as whipping boys by senior management to harass the staff into giving them the performance they expect. The junior manager then ends up on the receiving end of all the staff grievances about all manner of things, mostly ones they have no control over. It's a shoot job, both in terms of actual hourly remuneration and work/life balance.