Not just Honda. Most car makers seem to charge the public ridiculous prices for parts. The trade can often get them 40% or more cheaper. But even if a plastic hubcap is reduced to £90 thats still ridiculous. They are relying on owners of newish cars biting the bullet if they only need one and probably not realising a Honda original alloy wheel may not cost much more.
Plastic bumpers can reduce repair costs if they save the need for cutting out and welding in metal panels. And particularly useful for older cars that can be repaired using used parts without becoming a 'cut and shut' of yesteryear.
It seems to me that Insurers, approved body shops and manufacturers have a cosy relationship, with each taking their share of a lucrative 'gravy boat', with consumers paying in higher insurance premiums. If the value of the car and cost of repair limits their bonanza the car is 'written off' to a secondary motor trade who repair it on a more realistic budget for resale.