Senna is a bad example
They knew exactly how dangerous open-wheel (F1) racing was at the time when Senna died. Roland Ratzenberger died during qualifying the day before.
Senna's and Ratzenberger's deaths were at the end of what Martin Brundle has described as F1's "light-bulb" years: if a driver died, they slotted another one in and carried on.
At least two marshals have died at F1 race weekends since Senna as well as Bianchi (and test driver Maria de Villota, whose death was recorded as due to her injuries sustained in a crash during testing for Marussia). Anthoine Hubert was killed in an F2 race at Spa in 2019.