Lack of pre-Jaehaerys roads

[Jaak]

Why were roads so conspicuously absent in Westeros till Jaehaerys?

Gardeners or Lannisters might have been able to afford some - and would have needed them, more urgently than Jaehaerys.

[F1re4ndBl00d]

Well, for thousands of years, Westeros was divided. Countless kingdoms, focusing on waging war on their neighbors. So infrastructure wasn't exactly a concern. Also, roads could be considered a weakness in constant war, as opposing armies could very well use them to reach objectives faster. Now, after the Targaryen conquest, the realm was united and the need for infrastructure, especially roads, was great. Aegon I was focused on keeping shit together and consolidating the Targaryen rule, Aenys I had his conflict with the Faith and he wasn't such a great administrator. Maegor I... well, let's not go there. So, Jaehaerys I was the one who would invest time and money in roads.

[Jaak]

4 minutes ago, F1re4ndBl00d said:

Well, for thousands of years, Westeros was divided. Countless kingdoms, focusing on waging war on their neighbors. So infrastructure wasn't exactly a concern. Also, roads could be considered a weakness in constant war, as opposing armies could very well use them to reach objectives faster.

Both.

Reach is something like, 600 miles Highgarden to Tumbleton and 330 miles Highgarden to Oldtown.

When the Dornish raid Horn Hill, how are the Oakhearts and Osgreys supposed to ride to help? Riding 600 miles takes a month, by which time Tarly is heroically outnumbered and dead, and Dornish safely back in Red Mountains.

Yes, roads could be considered a weakness when used by enemies. So can absence of roads, which prevents the defenders from calling their banners.

An obvious solution for the Gardeners might be to build 500 miles of road from Old Oak to Horn Hill - and desist from building the last 50 miles Horn Hill to border, or beyond to Blackmont.

4 minutes ago, F1re4ndBl00d said:

Now, after the Targaryen conquest, the realm was united and the need for infrastructure, especially roads, was great.

Less than before!

In time of Gardeners, if Dornish raided around Oldtown, then Footly of Tumbleton would have needed 3 days to get the raven - and, assuming 20 miles per day to ride on friendly country, 47 days to ride to Oldtown. Total 50 days.

Under Targaryens, Jaehaerys and Alysanne are specifically established to need 3 days to fly by dragons to fly the 1090 miles King´s Landing to Oldtown to bury High Lickspittle and blackmail the Faith to not elect Mattheus.

Total 6 days to respond to a political emergency (or a military one, Vermithor´s speed would have been the same if it had been a Dornish raid) at speed of dragon vs. 50 days to respond by cavalry changes the assumptions about viability and profitability of raiding, feuding or revolting. And about the need for roads to facilitate mobilization of cavalry.

[Seaserpent]

12 hours ago, F1re4ndBl00d said:

Well, for thousands of years, Westeros was divided. Countless kingdoms, focusing on waging war on their neighbors. So infrastructure wasn't exactly a concern. Also, roads could be considered a weakness in constant war, as opposing armies could very well use them to reach objectives faster. Now, after the Targaryen conquest, the realm was united and the need for infrastructure, especially roads, was great. Aegon I was focused on keeping shit together and consolidating the Targaryen rule, Aenys I had his conflict with the Faith and he wasn't such a great administrator. Maegor I... well, let's not go there. So, Jaehaerys I was the one who would invest time and money in roads.

Most of your point i agree with, but roads were very important before AC, because for example goods from Gulltown or other cities needed transport to the other castles. Its not said there weren't roads at all but not international highways only normal roads. If there weren't good roads already people from acorn hall and blackhaven would have starved to death.

[The Dragon Demands]

They explain that:  the Faith Militant was there for centuries, to help travelers and trade caravans along the more primitive local roads.

When they got rid of the Faith Militant, overland travel ground to a halt.  Jaehaerys realized they needed high-quality, official highways to speed travel along (bandits usually ambush when travelers get slowed down by muddy local roads; a real highway that stays in good condition you can speed along and it doesn't need a standing guard force like the Faith Militant).