Water use and toilets

[kf4rca]

In my township, they offered rebates on the cost of a new toilet (not the installation). But plumbers cautioned against installing these unless you had a new sewer line (PVC) installed. The problem is the old sewer line pipes are not smooth enough to pass the effluent to the street. PVC use started in about 1980 here and many older homes have concrete lines, which was the going thing 60 years ago.

[Telecolor 3007]

But what is the problem with the old pipes and the new toilets.
Still I can't really figure if the flushmeter really needs and classic style U.S.A. toilet.
@ zeno : going around rules is common in Romania. Some reasons are common with the U.S.A., others because particular thing 'round here.