Hi! Number one is actually strange...it should be, "The straggling unmade road was lined on either side by houses." And yes, the road is the grammatical subject. Imagine a long road...and on both the left and right side of the road there are many houses "lining" (following / demarcating) the road.
The second example is also a passive. And here, too, the lake side is the grammatical subject.
I think one big problem with these sentences is that they seem to come from an English language grammar book. My advice is to NEVER use examples in textbooks as real or accurate samples of English. Instead, read a blog article online. Read a travel site. Read anything that is written to communicate...then find examples in there. Good question, though!