The EU is a critical source of funding for major infrastructure projects, especially for newer members who also have access to convergence funds. Road projects are expensive not only because of costs in design, land acquisition, and construction materials, but because they require large amounts of labor over several years. While it's often the same multinational consortia who bid on and win such construction projects, these firms aren't set up to do everything by themselves, and partner with local subcontractors for much of the work. The way work gets subcontracted makes this process vulnerable to corruption and graft. But sometimes it's the big consortia that get themselves into a problematic situation: just read up on Bechtel and Viaduct at Suplacu de Barcău.
EU transport and convergence funds might be a big help, but they do come with a few strings attached: they have to be used for projects that can be justified though a regional or EU-wide lens. On top of the slow pace of progress on the matter, Moldavia has an unfortunate geographic situation that puts it far away from the most important transit corridors -- the TEN-T corridors -- that EU desires to prioritize. In Romania's case, this means that connections towards Hungary and Bulgaria have so far made more progress than connections towards Ukraine and Moldova.
[1] https://www.euronews.com/2018/12/07/which-countries-in-europ...