There are actual lactation consultants in the hospitals there. Whereas our hospital midwives are too run off their feet to be able to offer breastfeeding advice, and if they do have time, only about half of them have useful knowledge about it, too many give unhelpful advice or "support" - do they still grab the baby and your boob and try to mash the two together and then appear surprised when it doesn't work? I don't know that I've heard of that particular speciality lately but I have heard the old rubbish about not letting them feed for more than X minutes every Y hours in case they get tired and the constant insistence on top ups, for spurious reasons and completely without any plan to solve the underlying issue is still rife. Tongue ties, poor latch frequently missed leading to painful feeds, unsettled babies, poor weight gain. Incorrect/inappropriate advice can lead to poor milk transfer or low milk supply and introduction of formula without a long term plan (and I have never, ever heard of top ups being suggested WITH a long term plan - I hope it DOES happen, somewhere - but I've never heard of it) tends to lead to full formula feeding before long.
Then post birth, I do think the overall support in the UK is better as you can have community midwives come out to you (I found these tend to be better at breastfeeding support, because they have more time, but some still lack the knowledge) and then health visitors, but the breastfeeding specific support - again health visitors usually have shocking breastfeeding knowledge, there are a handful of good ones, but again, if you get given poor info here, you are potentially set up to fail. And if you ask your health visitor or midwife about ongoing breastfeeding support, you'll be extremely lucky if they even know any exists. Whereas in the US, while you don't have the support from the hospital and there are no community health visitor type services, most health insurance packages will pay for lactation consultant services and women know that lactation consultants exist because they will have been offered their services in hospital. So if they decide to seek further advice, while they may still encounter poor advice, for example through their paediatrician, that's not the only option presented to them.
It's not about leaving work because many working mothers in the US pump milk - many many more than in the UK to the extent that this is pretty much normal. By the time mothers are returning to work in the UK their breastfeeding status is irrelevant because the biggest drop offs happen in the first 2 weeks and then 6 weeks. It's very rare to return to work that early in the UK. In addition almost half of mothers in the UK take over 9 months' maternity leave, at which point a child can simply be left with food and drink during the day with their milk intake largely confined to first and last thing at morning/night. (I couldn't find a figure any more up to date than 2008, so average maternity leave might be shorter these days).
More mothers start breastfeeding in the UK but then at every comparison point after that our rates are lower than in the US (despite higher start rate) - meaning our drop off rate is much, much sharper and this is despite much heavier formula manufacturing there and lack of state funded healthcare - and I truly believe it is because our front line support only sometimes helps, often misses problems, often actively harms individual women's breastfeeding journey, and most women are not aware of other (better quality) sources of breastfeeding support. Whereas in the US, although the front line support is not available to all women where it is available it tends to be good, and women tend to be aware of (even if not all are able to access) the availability of high quality support ongoing.