There are better omni directional antennas than the RV Jensen model and some can capture enough signal strength that would allow mounting inside an RV, but line of sight and less obstructions will always win. Directional antennas will pick up a signal better than omni but require adjustment when switching between stations broadcasting from different azimuths. In my home, I have an omni in the attic with a booster/amplifier that feeds the top floor. One floor lower, the television has second smaller booster to condition the line loss of the longer antenna run. It takes a little calculation to figure out line and connector losses, optimum amplifier inputs and amplifier output gains but works well.
RV manufacturers could do the same as I did above, but I think few have RF backgrounds and they just throw together some off the shelf parts that makes a hit or miss system.
BTW: I read some misconceptions about frequencies above. VHF is a lower frequency than UHF. Lower frequencies typically can travel farther because they will bounce off objects instead of getting absorbed into them like the higher frequencies. Because more of the digital stations are in the UHF band they are harder to receive than the analog stations that mostly occupied the VHF band. The higher the frequency, the more information it can carry in the same amount of bandwidth. This allows for closer channel spacing in the higher frequencies allowing for more channels or less bandwidth for that application.
