There has a phenomenal race to the bottom in terms and conditions in ground handling meaning meaning that motivated and able staff won't stay as the conditions are awful. BA and Midland used to self handle with staff who bought into the brand and had some judgement and latitude. Nowadays the market is so competitive that they simply dress third parties up in uniforms, pay them peanuts and don't allow them to stray one inch from their SLAs. Like cabin crew, it was a career choice for many, however newcomers to market without these legacy costs meant this was uncompetitive. Result everything outsourced, able and loyal people left and well you can see the results as Menzies, Servisair, Swissport and DNATA prostitute themselves ever lower.
The staff at handling agents themselves are excellent, everyone I work with are highly professional and very capable of their roles. However, as you stated, the handling agents and airlines hold them back.
No appreciation is given from the airline or handling agent to the staff, and the only time you'll be called into the office is when you've f#cked up.
This type of management just further reduces the levels of customer service given. Why would I push the boat out and try to accept a late pax when the only thing I'm letting myself in for is a bollocking when the flight pushes a minute or two late?