There are no practical reasons to show respect for the dead - you don’t get anything and the person is dead, so it makes no sense

Evidence

What is the biological logic behind the respect of the dead? (Philosophy Stack Exchange)

corroborated: 2 independent passages support this claim
XREF: connects to: Small acts of decorum toward corpses matter more than practical logic — Julien Gracq, Balcony in the Forest, 483; We should respect corpses because violating them would be a violation of human dignity, and it is still a violation — What is the philosophical basis for respect of human corpses; Posthumous dignity is not a right; the dead do not have rights and therefore no right to either posthumous dignity or posthumous respect. — The posthumous dignity of dead persons (+2 more)

We should respect corpses because violating them would be a violation of human dignity, and it is still a violation (similarity 0.90)
Posthumous dignity is not a right; the dead do not have rights and therefore no right to either posthumous dignity or posthumous respect. (similarity 0.89)
Posthumous dignity is not a right held by the dead but is the reason why the living have duties of respect and protection toward the dead. (similarity 0.88)
Not all legal regulations regarding treatment of human corpses are spelled out in the language of dignity; some offenses express special disrespect against the deceased (similarity 0.86)
We have a duty to treat the dead with dignity as a duty deriving from our good will, independent of religious considerations or concerns of virtue. (similarity 0.83)
Moral and philosophical conceptions of dignity hold that a human being is entitled to ethical treatment in all phases of life and even through death. (similarity 0.79)
Human remains hold a certain sacredness and professional ethics and law (NAGPRA) require they be treated with dignity and respect regardless of the deceased’s ability to hold rights. (similarity 0.78)
The common law already recognizes various posthumous rights (testamentary freedom, publicity, reproductive autonomy) and the categorical exclusion of the dead from constitutional protection is… (similarity 0.78)