By default, the public role (which is assigned to everybody in the DB) allows creating objects in the public schema. You can revoke this.
It is indeed a good practice to remove every rights from the public role, and to assign the desired privileges explicitly.
REVOKE ALL ON DATABASE myDB FROM PUBLIC;
REVOKE ALL ON SCHEMA public FROM PUBLIC;
REVOKE ALL ON ...
This problem is a very common one when using huge graphs with pgrouting and a limited amount of RAM.
One solution (which may be automated with Python - but not necessarily) would be to use the rows_where parameter that is available in the function (see documentation at Selecting rows using rows_where parameter).
With this parameter you can split up the ...
Try to reinstall PostGIS by the following executable on this page : http://download.osgeo.org/postgis/windows/pg12/
The download will allow you to get the necessary dll files.
When PgAdmin4 was released, when you installed PostGIS with StackBuilder, some files were missing. They updated the executable a few days later and the problem was solved.
First, you can identify for each point the nearest line by using the postgis ST_Distance function (geometry_point,geometry_line) and a LIMIT 1 to keep only the nearest line.
In a second step, thanks to an attribute join, you will be able to add speed to your lines.
If you need help in executing these requests, don't hesitate to ask.