Money money money

That's one thing that Trimet has, is bucket loads of money. (except to pay for their promises to their retirees).
Trimet is the 'pass through' agency for lots of federal money.
Here they fund various small shuttle services:

• Tualatin Chamber of Commerce’s Tualatin Shuttle - $295,026
  Tualatin – Transit Commute Service
  The Tualatin Chamber of Commerce has successfully operated the Tualatin Shuttle since 1997. TriMet provides north-south transit service near the town center, however Tualatin severely lacks east-west service to the Northwest quadrant of town identified by TriMet as a “Target Employment Area for JARC Funded Projects.” This area of Tualatin has the greatest concentration of jobs not directly served by TriMet. It attracts significant traffic due to the concentration of jobs, location between I-5 and Highway 99W, and lack of TriMet service.In an effort to provide service to the jobs in this area, the JARC grant will be used to continue vital shuttle service during weekday peak hours that is free to riders.

• Swan Island Business Association’s Swan Island Evening Shuttle - $307,487
  Portland -Transit Commute Service
  The Swan Island Evening Shuttle provides a last-mile shuttle service between the Rose Quarter Transit Center and the Swan Island employment area via Basin Avenue weekday evenings between 6:30 p.m. and midnight.The Swan Island Evening Shuttle, which serves shift times when TriMet service is not offered, connects to all four MAX lines, Portland Streetcar and six TriMet bus lines on Swan Island at Anchor Street (Line 72), at the Albina/Mississippi MAX station (Yellow Line & Line 35) and at the Rose Quarter Transit Center (Red, Blue & Green lines; bus lines 4, 8, 35, 44, and 77; and C-Tran 157).

• Clackamas Community College’s (CCC) Green Line Shuttle - $90,000
  Clackamas County – Transit Commute Service
  The CCC Green Line Shuttle runs express service between the college’s main campus in Oregon City and the MAX Green Line terminus at Clackamas Town Center. It is full during rush hours. Seventy-two percent of incoming CCC students receive financial aid. Slightly more than half of these students live below the federal poverty level and 42 percent work more than 20 hours a week. The shuttle service provides a direct trip that is not available on TriMet and connects the under-served area around Clackamas Community College to the MAX service.                                            

• Ride Connection’s Forest Grove, Cornelius and Tigard Connector Service – $307,487
  Forest Grove – Transit Commute Service
  Ride Connection’s Connector Service provides transportation service to low-income areas that do not have transit service, helping individuals traveling for employment, job training or employment-related activities. Riders are able to connect to and utilize the TriMet system and create local community connections. Last-mile connector service will be made available in urbanized areas in Forest Grove, Cornelius and Tigard.
• Trimet publication here