To answer the original question- yes it is training, for example when the new government decide on a curriculum and various initiatives a training day may include stuff on those, also, if the school buys new kit there may be training on how to use it. Long term plans may be drawn up (these often cover the whole school so teachers can't do them on their own).
Also- although teachers do ten to take the woe me approach and I can see why this annoys some people it is more in response to people who think that teachers work the same hours the children are in school then lounge about during the holidays (yes some do) but many teachers arrive at school between 7.30 and 8.00 then leave at around 5.00 taking work with them. I've never seen a teacher spend the whole of lunch time in the staff room, there is always stuff to be done. Also, many teachers (speaking about primary now) will devote at least one week of summer holidays to going into school to plan with their classroom assistants and get stuff ready for their new class e.g. peg labels, drawer labels, Learning Journey Books, work books, cleaning and organising storage and toys. And will also spend many other holidays planning, making assessments getting records up to date etc.
Also- in response to arranging childcare, if you don't want to have to arrange childcare don't have children; surely having been through the education system yourself you know that there are holidays (which may I add children need, it's not just so teachers can have time off)?