Yes we had Kindergarten. It was pretty much compulsory to send your child to one year of Kindergarten (i.e. age 6-7) and you could choose to send your child for two years (i.e. age 5-7). However Kindergarten was completely play based - no letters or numbers at all. And we went for about 15 hours per week, so far from full time. And that seemed like lots.
I agree with noramum that once school started, it was at speed, academically speaking. But, again in agreement, it is much easier for 7 year olds to learn things like reading and arithmetic, than it is for 4 year olds.
However, even at age 7, school was not anything near full time. I went to school 6 mornings per week (including Saturday, not very common anymore) and 2 afternoons, which increased to 3 afternoons at secondary school age. Everybody went home for lunch (and came back to school if they had afternoon lessons).
So that kind of illustrates that when I was young, it was very hard even when your kids were school age i.e. 7+, for both parents to have full time jobs. It was expected that one parent would be at home, cooking lunch, looking after the one child who had the afternoon off (e.g. my afternoon sessions were on Tuesdays and Thursdays and DSis' sessions were on Mondays and Fridays... meaning one child out of school for every afternoon of the week, and both on Wednesday afternoon) etc.
At Kindergarten age it was even harder, as there was very little in terms of daycare available. Unless you had family locally.
Things have changed a bit since then. But for example my nephew just turned six. He started 'forest school' last August, at 5.4, and will continue there for a second year next August. He will then move to school when he is 7.4. His forest school is entirely outside, has no letters or numbers, and this year runs for 4x 3h sessions per week, next year being upped to 6x 3h sessions, including one lunch. The 3h sessions are seen as particularly long, the regular Kindergarten will only hold 2.5 hour sessions, but as children travel quite far for the forest school, they have fewer but longer sessions.
DSil has managed by being SAHM. She is now going back to work part-time, which is only possible as her MIL lives in the same house.
DS who is 4.8 can currently read and do arithmetic MUCH better than my nephew who is 6. I imagine this gap will increase until DNephew starts school in over a year's time - DS will then be starting Y2. But I have no doubts that DNephew will catch up very quickly once he does start school. And would actually prefer for DS to be messing around in the mud for now, instead of counting to 100.
Nowadays there are many more daycare solutions than there used to be when I was little. Nurseries, childminders, often subsidised but still extremely expensive. But as no-one goes off to school before age 6, nurseries etc. are structured around the needs of these older children too, and are not just intended for the up-to-five year olds, as our nurseries are here.